Government Communications Headquarters
|Formed||1919 as the GC&CS|
|Jurisdiction||Her Majesty's Government|
|Headquarters||Hubble Road, Cheltenham, England, United Kingdom
|Employees||5,564 (31 March 2015)|
|Annual budget||Single Intelligence Account (£2.6 billion in 2014–2015 financial year)|
The Government Communications Headquarters (GCHQ) is a British intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance to the British government and armed forces. Based in "The Doughnut", in the suburbs of Cheltenham, GCHQ is the responsibility of the UK Secretary of State for Foreign and Commonwealth Affairs, but it is not a part of the Foreign Office and its Director ranks as a Permanent Secretary.
GCHQ was originally established after the First World War as the Government Code and Cypher School (GC&CS) and was known under that name until 1946. During the Second World War it was located at Bletchley Park, where it was famed for its role in the breaking of the German Enigma codes. Currently there are two main components of the GCHQ, the Composite Signals Organisation (CSO), which is responsible for gathering information, and the National Cyber Security Centre (NCSC), which is responsible for securing the UK's own communications. The Joint Technical Language Service (JTLS) is a small department and cross-government resource responsible for mainly technical language support and translation and interpreting services across government departments. It is co-located with GCHQ for administrative purposes.
In 2013, GCHQ received considerable media attention when the former National Security Agency contractor Edward Snowden revealed that the agency was in the process of collecting all online and telephone data in the UK via the Tempora programme. Snowden's revelations began a spate of ongoing disclosures of global surveillance.
- 1 Structure
- 2 History
- 3 CESG and NCSC
- 4 Joint Technical Language Service
- 5 International relationships
- 6 Legal basis
- 7 Constitutional legal case
- 8 Leadership
- 9 Stations and former stations
- 10 In popular culture
- 11 See also
- 12 Notes and references
- 13 Bibliography
- 14 External links
- Sigint missions: comprising maths and cryptanalysis, IT and computer systems, linguistics and translation, and the intelligence analysis unit
- Enterprise: comprising applied research and emerging technologies, corporate knowledge and information systems, commercial supplier relationships, and biometrics
- Corporate management: enterprise resource planning, human resources, internal audit, and architecture
- Communications-Electronics Security Group
Government Code and Cypher School (GC&CS)
During the First World War, the United Kingdom's Army and Navy had separate signals intelligence agencies, MI1b and NID25 (initially known as Room 40) respectively. In 1919, the Cabinet's Secret Service Committee, chaired by Lord Curzon, recommended that a peace-time codebreaking agency should be created, a task given to the then-Director of Naval Intelligence, Hugh Sinclair. Sinclair merged staff from NID25 and MI1b into the new organisation, which initially consisted of around 25–30 officers and a similar number of clerical staff. It was titled the "Government Code and Cypher School", a cover-name chosen by Victor Forbes of the Foreign Office.
Alastair Denniston, who had been a member of NID25, was appointed as its operational head. It was initially under the control of the Admiralty and located in Watergate House, Adelphi, London. Its public function was "to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision", but also had a secret directive to "study the methods of cypher communications used by foreign powers". GC&CS officially formed on 1 November 1919, and produced its first decrypt on 19 October.
Before the Second World War, GC&CS was a relatively small department. By 1922, the main focus of GC&CS was on diplomatic traffic, with "no service traffic ever worth circulating" and so, at the initiative of Lord Curzon, it was transferred from the Admiralty to the Foreign Office. GC&CS came under the supervision of Hugh Sinclair, who by 1923 was both the Chief of SIS and Director of GC&CS. In 1925, both organisations were co-located on different floors of Broadway Buildings, opposite St. James's Park. Messages decrypted by GC&CS were distributed in blue-jacketed files that became known as "BJs".
In the 1920s, GC&CS was successfully reading Soviet Union diplomatic ciphers. However, in May 1927, during a row over clandestine Soviet support for the General Strike and the distribution of subversive propaganda, Prime Minister Stanley Baldwin made details from the decrypts public.
During the Second World War, GC&CS was based largely at Bletchley Park in present-day Milton Keynes working on, most famously, the German Enigma machine and Lorenz ciphers, but also a large number of other systems. In 1940, GC&CS was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems. Senior staff included Alastair Denniston, Oliver Strachey, Dilly Knox, John Tiltman, Edward Travis, Ernst Fetterlein, Josh Cooper, Donald Michie, Alan Turing, Joan Clarke, Max Newman, William Tutte, I. J. (Jack) Good, Peter Calvocoressi and Hugh Foss.
An outstation in the Far East, the Far East Combined Bureau was set up in Hong Kong in 1935, and moved to Singapore in 1939. Subsequently, with the Japanese advance down the Malay Peninsula, the Army and RAF codebreakers went to the Wireless Experimental Centre in Delhi, India. The Navy codebreakers in FECB went to Colombo, Ceylon, then to Kilindini, near Mombasa, Kenya.
GC&CS was renamed the "Government Communications Headquarters" in June 1946.
Post Second World War
GCHQ was at first based in Eastcote, but in 1951 moved to the outskirts of Cheltenham, setting up two sites there – Oakley and Benhall. Duncan Campbell and Mark Hosenball revealed the existence of GCHQ in 1976 in an article for Time Out; GCHQ retaliated by forcibly deporting Hosenball from the UK. GCHQ had a very low profile in the media until 1983 when the trial of Geoffrey Prime, a KGB mole within GCHQ, created considerable media interest.
Since the days of the Second World War, US and British intelligence have shared information. For the GCHQ this means that it shares information with, and gets information from, the National Security Agency (NSA) in the United States.
Public key encryption
Early in the 1970s, the concept for public key encryption was developed and proven by James H. Ellis, a GCHQ staff member since 1952, who lacked the necessary number theory expertise necessary to build a workable system. Subsequently, a feasible implementation scheme via an asymmetric key algorithm was invented by another staff member Clifford Cocks, a mathematics graduate. This fact was kept secret until 1997.
Trade union disputes
In 1984, GCHQ was the centre of a political row when the Conservative government of Margaret Thatcher prohibited its employees from belonging to a trade union. It was claimed that joining a union would be in conflict with national security. A number of mass national one-day strikes were held to protest this decision, seen as a first step to wider bans on trade unions. Appeals to British Courts and European Commission of Human Rights were unsuccessful. The government offered a sum of money to each employee who agreed to give up their union membership. Appeal to the ILO resulted in a decision that government's actions were in violation of Freedom of Association and Protection of the Right to Organise Convention.
The ban was eventually lifted by the incoming Labour government in 1997, with the Government Communications Group of the Public and Commercial Services (PCS) Union being formed to represent interested employees at all grades. In 2000, a group of 14 former GCHQ employees, who had been dismissed after refusing to give up their union membership, were offered re-employment, which three of them accepted.
Post Cold War
1990s: Post-Cold War restructuring
The Intelligence Services Act 1994 placed the activities of the intelligence agencies on a legal footing for the first time, defining their purpose, and the British Parliament's Intelligence and Security Committee was given a remit to examine the expenditure, administration and policy of the three intelligence agencies. The objectives of GCHQ were defined as working as "in the interests of national security, with particular reference to the defence and foreign policies of Her Majesty's government; in the interests of the economic wellbeing of the United Kingdom; and in support of the prevention and the detection of serious crime". During the introduction of the Intelligence Agency Act in late 1993, the former Prime Minister Jim Callaghan had described GCHQ as a "full blown bureaucracy", adding that future bodies created to provide oversight of the intelligence agencies should "investigate whether all the functions that GCHQ carries out today are still necessary."
In late 1993 civil servant Michael Quinlan advised a deep review of the work of GCHQ following the conclusion of his "Review of Intelligence Requirements and Resources", which had imposed a 3% cut on the agency. The Chief Secretary to the Treasury, Jonathan Aitken, subsequently held face to face discussions with the intelligence agency directors to assess further savings in the wake of Quinlan's review. Aldrich (2010) suggests that Sir John Adye, the then Director of GCHQ performed badly in meetings with Aitken, leading Aitken to conclude that GCHQ was "suffering from out-of-date methods of management and out-of-date methods for assessing priorities". GCHQ's budget was £850 million in 1993, (£1.56 billion as of 2015) compared to £125 million for MI5 and SIS. In December 1994 the businessman Roger Hurn was commissioned to begin a review of GCHQ, which was concluded in March 1995. Hurn's report recommended a cut of £100 million in GCHQ's budget; such a large reduction had not been suffered by any British intelligence agency since the end of World War II. The J Division of GCHQ, which had collected SIGINT on Russia, disappeared as result of the cuts. The cuts had been mostly reversed by 2000 in the wake of threats from violent non-state actors, and risks from increased terrorism, organised crime and illegal access to nuclear, chemical and biological weapons.
David Omand became the Director of GCHQ in 1996, and greatly restructured the agency in the face of new and changing targets and rapid technological change. Omand introduced the concept of "Sinews" (or "SIGINT New Systems") which allowed more flexible working methods, avoiding overlaps in work by creating fourteen domains, each with a well-defined working scope. The tenure of Omand also saw the planning and the creation of The Doughnut, GCHQ's modern headquarters. Located on a 176-acre site in Benhall, near Cheltenham, The Doughnut would be the largest building constructed for secret intelligence operations outside the United States.
Operations at GCHQ’s Chum Hom Kwok listening station in Hong Kong ended in 1994. GCHQ's Hong Kong operations were extremely important to their relationship with the NSA, who contributed investment and equipment to the station. In anticipation of the transfer of Hong Kong to the Chinese government in 1997, the Hong Kong stations operations were moved to Geraldton in Australia.
Operations that utilised GCHQ's intelligence-gathering capabilities in the 1990s included the monitoring of communications of Iraqi soldiers in the Gulf War, of dissident republican terrorists and the Real IRA, of the various factions involved in the Yugoslav Wars, and of the criminal Kenneth Noye. In the mid 1990s GCHQ began to assist in the investigation of cybercrime.
2000s: Coping with the Internet
At the end of 2003, GCHQ moved to a new circular HQ (popularly known as "The Doughnut"). At the time, it was the second-largest public-sector building project in Europe, with an estimated cost of £337 million. The new building, which was designed by Gensler and constructed by Carillion, is the base for all of GCHQ's Cheltenham operations.
The public spotlight fell on GCHQ in late 2003 and early 2004 following the sacking of Katharine Gun after she leaked to The Observer a confidential email from agents at the United States' National Security Agency addressed to GCHQ agents about the wiretapping of UN delegates in the run-up to the 2003 Iraq war.
GCHQ gains its intelligence by monitoring a wide variety of communications and other electronic signals. For this, a number of stations have been established in the UK and overseas. The listening stations are at Cheltenham itself, Bude, Scarborough, Ascension Island, and with the United States at Menwith Hill. Ayios Nikolaos Station in Cyprus is run by the British Army for GCHQ.
As revealed by Edward Snowden in The Guardian, GCHQ spied on foreign politicians visiting the 2009 G-20 London Summit by eavesdropping phonecalls and emails and monitoring their computers, and in some cases even ongoing after the summit via keyloggers that had been installed during the summit. Some of the information gained has been passed on to British politicians.
According to Edward Snowden, GCHQ has two principal umbrella programs for collecting communications:
- "Mastering the Internet" (MTI) for Internet traffic, which is extracted from fiber-optic cables and can be searched by using the Tempora computer system.
- "Global Telecoms Exploitation" (GTE) for telephone traffic.
GCHQ also has had access to the US internet monitoring programme PRISM since at least June 2010. PRISM is said to give the National Security Agency and FBI easy access to the systems of nine of the world's top internet companies, including Google, Facebook, Microsoft, Apple, Yahoo, and Skype.
In February 2014, The Guardian, based on documents provided by Snowden, revealed that GCHQ had indiscriminately collected 1.8 million private Yahoo webcam images from users across the world. In the same month NBC and The Intercept, based on documents released by Snowden, revealed the Joint Threat Research Intelligence Group and the CNE units within GCHQ. Their mission was cyber operations based on "dirty tricks" to shut down enemy communications, discredit, and plant misinformation on enemies. These operations were 5% of all GCHQ operations according to a conference slideshow presented by the GCHQ.
Soon after becoming Director of GCHQ in 2014, Robert Hannigan wrote an article in the Financial Times on the topic of internet surveillance, stating that "however much [large US technology companies] may dislike it, they have become the command and control networks of choice for terrorists and criminals" and that GCHQ and its sister agencies "cannot tackle these challenges at scale without greater support from the private sector", arguing that most internet users "would be comfortable with a better and more sustainable relationship between the [intelligence] agencies and the tech companies". Since the 2013 global surveillance disclosures, large US technology companies have improved security and become less co-operative with foreign intelligence agencies, including those of the UK, generally requiring a US court order before disclosing data. However the head of the UK technology industry group techUK rejected these claims, stating that they understood the issues but that disclosure obligations "must be based upon a clear and transparent legal framework and effective oversight rather than, as suggested, a deal between the industry and government".
In 2017, U.S. Press Secretary Sean Spicer alleged that GCHQ had conducted surveillance on U.S. President Donald Trump, basing the allegation on statements made by a media commentator during a Fox News segment. The U.S. government formally apologised for the allegations and promised they would not be repeated. However, surveillance of Russian agents did pick up contacts made by Trump's campaign team in the run up to his election, which was passed on to U.S. agencies.
CESG and NCSC
CESG (originally Communications-Electronics Security Group) was a group within GCHQ which provided assistance to government departments on their own communications security: CESG was the UK National Technical Authority for information assurance, including cryptography. CESG did not manufacture security equipment, but worked with industry to ensure the availability of suitable products and services, while GCHQ itself funded research into such areas, for example to the Centre for Quantum Computing at Oxford University and the Heilbronn Institute at the University of Bristol.
In 2016, the National Cyber Security Centre was established under GCHQ, but located in London, as the UK’s authority on cyber security. It absorbed and replaced the CESG as well as the Centre for Cyber Assessment (CCA), Computer Emergency Response Team UK (CERT UK) and the cyber-related responsibilities of the Centre for the Protection of National Infrastructure (CPNI).
Joint Technical Language Service
The Joint Technical Language Service (JTLS) was established in 1955, drawing on members of the small Ministry of Defence technical language team and others, initially to provide standard English translations for organisational expressions in any foreign language, discover the correct English equivalents of technical terms in foreign languages and discover the correct expansions of abbreviations in any language.
The remit of the JTLS has expanded in the ensuing years to cover technical language support and interpreting and translation services across the UK Government and to local public sector services in Gloucestershire and surrounding counties. The JTLS also produces and publishes foreign language working aids under crown copyright and conducts research into machine translation and on-line dictionaries and glossaries.
The JTLS is co-located with GCHQ for administrative purposes.
GCHQ operates in partnership with equivalent agencies worldwide in a number of bi-lateral and multi-lateral relationships. The principal of these is with the United States (National Security Agency), Canada (Communications Security Establishment), Australia (Australian Signals Directorate) and New Zealand (Government Communications Security Bureau), through the mechanism of the UK-US Security Agreement, a broad intelligence-sharing agreement encompassing a range of intelligence collection methods.
GCHQ's legal basis is enshrined in the Intelligence Services Act 1994 Section 3 as follows:
(1) There shall continue to be a Government Communications Headquarters under the authority of the Secretary of State; and, subject to subsection (2) below, its functions shall be—
- (a) to monitor or interfere with electromagnetic, acoustic and other emissions and any equipment producing such emissions and to obtain and provide information derived from or related to such emissions or equipment and from encrypted material; and
- (b) to provide advice and assistance about—
- (i) languages, including terminology used for technical matters, and
- (ii) cryptography and other matters relating to the protection of information and other material, to the armed forces of the Crown, to Her Majesty's Government in the United Kingdom or to a Northern Ireland Department or to any other organisation which is determined for the purposes of this section in such manner as may be specified by the Prime Minister.
(2) The functions referred to in subsection (1)(a) above shall be exercisable only—
- (a) in the interests of national security, with particular reference to the defence and foreign policies of Her Majesty's Government in the United Kingdom; or
- (b) in the interests of the economic well-being of the United Kingdom in relation to the actions or intentions of persons outside the British Islands; or
- (c) in support of the prevention or detection of serious crime.
(3) In this Act the expression "GCHQ" refers to the Government Communications Headquarters and to any unit or part of a unit of the armed forces of the Crown which is for the time being required by the Secretary of State to assist the Government Communications Headquarters in carrying out its functions.
Activities that involve interception of communications are permitted under the Regulation of Investigatory Powers Act 2000; this kind of interception can only be carried out after a warrant has been issued by a Secretary of State. The Human Rights Act 1998 requires the intelligence agencies, including GCHQ, to respect citizens' rights as described in the European Convention on Human Rights.
The Prime Minister nominates cross-party Members of Parliament to an Intelligence and Security Committee. The remit of the Committee includes oversight of intelligence and security activities and reports are made directly to Parliament. Its functions were increased under the Justice and Security Act 2013 to provide for further access and investigatory powers.
Judicial oversight of GCHQ's conduct is exercised by the Investigatory Powers Tribunal. The UK also has an independent Intelligence Services Commissioner and Interception of Communications Commissioner, both of whom are former senior judges.
The Investigatory Powers Tribunal ruled in December 2014 that GCHQ does not breach the European Convention of Human Rights, and that its activities are compliant with Articles 8 (right to privacy) and 10 (freedom of expression) of the European Convention of Human Rights. However, the Tribunal stated in February 2015 that one particular aspect, the data-sharing arrangement that allowed UK Intelligence services to request data from the US surveillance programmes Prism and Upstream, had been in contravention of human rights law prior to this until two paragraphs of additional information, providing details about the procedures and safeguards, were disclosed to the public in December 2014.
Furthermore, the IPT ruled that the legislative framework in the United Kingdom does not permit mass surveillance and that while GCHQ collects and analyses data in bulk, it does not practice mass surveillance. This complements independent reports by the Interception of Communications Commissioner, and a special report made by the Intelligence and Security Committee of Parliament; although several shortcomings and potential improvements to both oversight and the legislative framework were highlighted.
Despite the inherent secrecy around much of GCHQ's work, investigations carried out by the UK government after the Snowden disclosures have admitted various abuses by the security services. A report by the Intelligence and Security Committee (ISC) in 2015 revealed that a small number of staff at UK intelligence agencies had been found to misuse their surveillance powers, in one case leading to the dismissal of a member of staff at GCHQ, although there were no laws in place at the time to make these abuses a criminal offence.
Later that year, a ruling by the IPT found that GCHQ acted unlawfully in conducting surveillance on two human rights organisations. The closed hearing found the government in breach of its internal surveillance policies in accessing and retaining the communications of the Egyptian Initiative for Personal Rights and the Legal Resources Centre in South Africa. This was only the second time in the IPT's history that it has made a positive determination in favour of applicants after a closed session.
At another IPT case in 2015, GCHQ conceded that "from January 2010, the regime for the interception/obtaining, analysis, use, disclosure and destruction of legally privileged material has not been in accordance with the law for the purposes of Article 8(2) of the European convention on human rights and was accordingly unlawful". This admission was made in connection with a case brought against them by Abdel Hakim Belhaj, a Libyan opponent of the former Gaddafi regime, and his wife Fatima Bouchar. The couple accused British ministers and officials of participating in their unlawful abduction, kidnapping and removal to Libya in March 2004, while Gaddafi was still in power.
It was further reported in 2015 that British intelligence services, including GCHQ, had been spying on MPs in defiance of laws prohibiting it. GCHQ had introduced a policy in March 2015 that did not require approval by the Prime Minister, or any Minister, before deliberately targeting the communications of a parliamentarian. This is despite then-Home Secretary, Theresa May, telling Parliament in 2014 that "Obviously, the Wilson doctrine applies to parliamentarians."
Constitutional legal case
A controversial GCHQ case determined the scope of judicial review of prerogative powers (the Crown's residual powers under common law). This was Council of Civil Service Unions v Minister for the Civil Service  AC 374 (often known simply as the "GCHQ case"). In this case, a prerogative Order in Council had been used by the prime minister (who is the Minister for the Civil Service) to ban trade union activities by civil servants working at GCHQ. This order was issued without consultation. The House of Lords had to decide whether this was reviewable by judicial review. It was held that executive action is not immune from judicial review simply because it uses powers derived from common law rather than statute (thus the prerogative is reviewable). Controversially, they also held that although the failure to consult was unfair, this was overridden by concerns of national security.
The following is a list of the heads of the operational heads of GCHQ and GC&CS:
- Alastair Denniston CMG CBE (1921 – February 1942) (continued as Deputy Director (Diplomatic and Commercial) until 1945).
- Sir Edward Travis KCMG CBE (February 1942 – 1952)
- Sir Eric Jones KCMG CB CBE (April 1952 – 1960)
- Sir Clive Loehnis KCMG (1960–1964)
- Sir Leonard Hooper KCMG CBE (1965–1973)
- Sir Arthur Bonsall KCMG CBE (1973–1978)
- Sir Brian John Maynard Tovey KCMG (1978–1983)
- Sir Peter Marychurch KCMG (1983–1989)
- Sir John Anthony Adye KCMG (1989–1996)
- Sir David Omand GCB (1996 –1997)
- Sir Kevin Tebbit KCB CMG (1998)
- Sir Francis Richards KCMG CVO DL (1998–2003)
- Sir David Pepper KCMG (2003–2008)
- Sir Iain Lobban KCMG CB (2008–2014)
- Robert Hannigan CMG (2014–2017)
- Jeremy Fleming (2017–Present)
Stations and former stations
- Current stations
- Former stations
In popular culture
The historical drama The Imitation Game featured Benedict Cumberbatch portraying Alan Turing's efforts to break the Enigma code as part of the Government Code and Cypher School, the forerunner of GCHQ.
- Hugh Alexander – head of the cryptanalysis division at GCHQ from 1949–1971
- RAF Digby
- RAF Intelligence
- UK Cyber Security Community
- Zircon, the cancelled GCHQ satellite project
- Operation Socialist
- Joint Operations Cell
Notes and references
- House of Commons (5 July 2016). Intelligence and Security Committee of Parliament Annual Report 2015–2016, page 14. Retrieved 23 October 2016.
- House of Commons (5 July 2016). Intelligence and Security Committee of Parliament Annual Report 2015–2016, page 10. Retrieved 12 January 2017.
- GCHQ – Welcome to GCHQ, gchq.gov.uk. Retrieved 7 July 2014.
- "A simple guide to GCHQ's internet surveillance programme Tempora".
- "MI5 veteran Jeremy Fleming named as new GCHQ head". News.sky.com. Retrieved 21 March 2017.
- Aldrich, 2010, p. 565
- (secondary) Leong, Angela (2007). The Disruption of International Organised Crime: An Analysis of Legal and Non-Legal Strategies. Ashgate Publishing. ISBN 0-7546-7066-X. Retrieved 19 April 2012.
- Gannon, Paul (2011). Inside Room 40: The Codebreakers of World War I. Ian Allen Publishing. ISBN 978-0-7110-3408-2.
- Johnson, 1997, p. 27
- Johnson, 1997, p. 44
- Johnson, 1997, p. 45 and Kahn, 1991, p. 82; these sources give different numbers for the initial size of the GC&CS staff
- Macksey, Kenneth (2003). The Searchers: How Radio Interception Changed the Course of Both World Wars. Cassell Military. p. 58. ISBN 0-304-36545-9.
- Smith, 2001, pp. 16–17
- Kahn, 1991, p. 82
- Denniston, Alastair G. (1986). "The Government Code and Cypher School Between the Wars". Intelligence and National Security. 1 (1): 48–70. doi:10.1080/02684528608431841.
- Smith, 2001, pp. 20–21
- Smith, 2001, pp. 18–19
- Aldrich, 2010, p. 18
- Gannon, Paul (2006). Colossus: Bletchley Park’s Greatest Secret. Atlantic Books. ISBN 978-1-84354-331-2.
- Alvarez, David (2001). "Most Helpful and Cooperative: GC&CS and the Development of American Diplomatic Cryptanalysis, 1941-1942". In Smith, Michael; Erskine, Ralph. Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer. Bantam Press. ISBN 978-0593049105.
- Smith, Michael (1998). Station X. Channel 4 books. p. 176. ISBN 0-330-41929-3.
- "History of GCHQ Cheltenham". GCHQ website 'About Us' pages. Archived from the original on 5 October 2006. Retrieved 29 June 2006.
- Duncan Campbell; Mark Hosenball (21 May 1976). "The Eavesdroppers" (PDF). Time Out. Retrieved 1 March 2016.
- Court ruling, "R v Secretary of State for the Home Department, ex parte Hosenball",  1 W.L.R. 766;  3 All E.R. 452. Lord Denning presiding judge, 29 March 1977.
- Aldrich, 2010, p. 382
- Murray, Craig (16 October 2007). Dirty Diplomacy. Scribner. p. 332. ISBN 978-1416548010.
- Singh, Simon. "Unsung Heroes of Cryptography". (originally published in The Sunday Telegraph)
- "EComHR Inadmissibility decision of EComHR on application no. 11603/85". 1987.
- "EComHR Inadmissibility decision of EComHR on application no. 11603/85 — The Facts". para. IV
- "Union representation". GCHQ website. Archived from the original on 9 May 2006. Retrieved 12 April 2006.
- "Sacked GCHQ workers win compensation". BBC News. 1 February 2000. Retrieved 12 April 2006.
- "ISC - About". The Intelligence and Security Committee of Parliament - About the Committee. Intelligence and Security Committee of Parliament. Retrieved 1 December 2013.
- "Intelligence Services Act 1994". Intelligence Services Act 1994. The National Archives. Retrieved 1 December 2013.
- "Hansard: December 1993 Intelligence Services Bill". Hansard. 9 December 1993.
- Aldrich 2010, p. 483
- Aldrich 2010, p. 493
- Aldrich 2010, p. 494
- UK Consumer Price Index inflation figures are based on data from Gregory Clark (2016), "The Annual RPI and Average Earnings for Britain, 1209 to Present (New Series)", MeasuringWorth.com.
- Aldrich 2010, p. 495
- Aldrich 2010, p. 505
- Aldrich 2010, p. 496
- Aldrich 2010, p. 9
- Aldrich 2010, p. 475
- Nigel West (31 August 2012). Historical Dictionary of Signals Intelligence. Scarecrow Press. pp. 27–. ISBN 978-0-8108-7391-9.
- Aldrich 2010, p. 473
- Aldrich 2010, p. 489
- "Carillion set for growth". BBC News. 19 September 2000.
- Aldrich, 2010, p. 521
- Campbell, Duncan (1981). "Phone tappers and the state". New Statesman: 54.
- Aldrich, 2010, p. 471
- "'Cavalier' GCHQ online spy centre loses 35 laptops". Computerworld UK. 12 March 2010.
- The Guardian: GCHQ intercepted foreign politicians' communications at G20 summits, 16 June 2013
- Philip Bump (21 June 2013). "The UK Tempora Program Captures Vast Amounts of Data – and Shares with NSA". The Atlantic Wire. Retrieved 23 June 2013.
- "Statement on GCHQ's Alleged Interception of Communications under the US PRISM Programme" (PDF). Intelligence and Security Committee of Parliament. 17 July 2013. Retrieved 17 December 2013.
- "Scale and significance of NSA snooping claims". BBC. 11 June 2013.
- "Optic Nerve: millions of Yahoo webcam images intercepted by GCHQ". 28 February 2014. Retrieved 2 March 2014.
- "Snowden Docs: British Spies Used Sex and 'Dirty Tricks'". NBC News. 7 February 2014. Retrieved 7 February 2014.
- "The Snowden Files: British Spies Used Sex and 'Dirty' Tricks" (PDF). NBC News Investigations. NBC. Retrieved 5 April 2015.
- Robert Hannigan (3 November 2014). "The web is a terrorist's command-and-control network of choice". Financial Times. Retrieved 3 November 2014.
- Sam Jones and Murad Ahmed (3 November 2014). "Tech groups aid terror, says UK spy chief". Financial Times. Retrieved 3 November 2014.
- David Barrett (4 November 2014). "Tech giants reject GCHQ boss Robert Hannigan's call for deal with government". Daily Telegraph. Retrieved 5 November 2014.
- ""Operation Karma Police": The British Government Spied on Everyone's Web Activity, Cell Phones. Massive GCHQ Data Bank". Global Research. 26 September 2015. Retrieved 28 September 2015.
- Croft, Jane (1 December 2015) UK spy agency GCHQ admits it carries out computer hacking. Financial Times
- Farrell, Henry (16 March 2017) Sean Spicer just suggested that Obama used British intelligence to spy on Trump. Not so much. Washington Post
- Blake, Aaron (16 March 2017) Sean Spicer's angry, lonely defense of Trump's wiretapping claim, annotated. Washington Post
- "US makes formal apology to Britain after White House accuses GCHQ of wiretapping Trump Tower". The Telegraph. 17 March 2017. Retrieved 17 March 2017.
- "White House apologizes to British government over spying claims". CNN. 17 December 2017. Retrieved 17 March 2017.
- "GCHQ dismisses 'utterly ridiculous' claim it helped wiretap Trump | US news". The Guardian. Retrieved 2017-04-13.
- "British spies were first to spot Trump team's links with Russia | UK news". The Guardian. Retrieved 2017-04-13.
- "British intelligence passed Trump associates' communications with Russians on to US counterparts". CNN. 14 April 2017. Retrieved 14 April 2017.
- "Heilbronn Institute for Mathematical Research". University of Bristol. Retrieved 30 August 2008.
- "CESG Service Catalogue". Retrieved 17 August 2015.
- "About us". National Cyber Security Centre. Retrieved 9 March 2017.
- Newmark, Peter (1991). About Translation. Multilingual Matters. p. 40. ISBN 1-85359-118-1.
- Schmid, Gerhard (11 July 2001). "On the existence of a global system for the interception of private and commercial communications (ECHELON interception system) – Temporary Committee on the ECHELON Interception System, (2001/2098(INI))" (PDF). European Parliament: Temporary Committee on the ECHELON Interception System. p. 194. Retrieved 27 March 2008.
- "Intelligence Services Act 1994". legislation.gov.uk. Retrieved 28 September 2015.
- "The Law". GCHQ. Retrieved 17 December 2013.
- "GCHQ does not breach human rights, judges rule". BBC. 5 December 2014. Retrieved 6 December 2014.
- "The Andrew Marr Show Interview: Theresa May, MP Home Secretary" (PDF). BBC. 23 November 2014. Retrieved 6 December 2014.
Well I guess what he’s talking about is the fact that for certain aspects and certain of the more intrusive measures that our security service and police have available to them – i.e. Intercept, intercepting people’s telephones and some other intrusive measures – the decision is taken by the Secretary of State, predominantly me. A significant part of my job is looking at these warrants and signing these warrants. I think it’s ... Some people argue that should be to judges....I think it’s very important that actually those decisions are being taken by somebody who is democratically accountable to the public. I think that’s an important part of our system. I think it’s a strength of our system.
- "The Intelligence and Security Committee of Parliament". Retrieved 14 December 2013.
- "Functions - Key role". The Investigatory Powers Tribunal. Retrieved 6 February 2015.
- "Intelligence Commissioners". Retrieved 14 December 2013.
- "IPT Ruling on Interception". GCHQ. Retrieved 6 February 2015.
- "GCHQ censured over sharing of internet surveillance data with US". BBC. 6 February 2015. Retrieved 6 February 2015.
- "UK-US surveillance regime was unlawful 'for seven years'". The Guardian. 6 February 2015. Retrieved 6 February 2015.
- "IPT rejects assertions of mass surveillance". GCHQ. 5 December 2014. Retrieved 7 February 2015.
- "List of judgments". Investigatory Powers Tribunal. 5 December 2014. Retrieved 7 February 2015.
1. A declaration that the regime governing the soliciting, receiving, storing and transmitting by UK authorities of private communications of individuals located in the UK which have been obtained by US authorities pursuant to Prism and/or Upstream does not contravene Articles 8 or 10 ECHR. 2. A declaration that the regime in respect of interception under ss8(4), 15 and 16 of the Regulation of investigatory Powers Act 2000 does not contravene Articles 8 or 10 ECHR and does not give rise to unlawful discrimination contrary to Article 14, read together with Articles 8 and/or 10 of the ECHR.
- "Statement by the Interception of Communications Commissioner's Office (IOCCO) on the publication of the Interception of Communications Commissioner's Report 2014" (PDF). 12 March 2015. Retrieved 14 March 2015."Report of the Interception of Communications Commissioner" (PDF). March 2015. Retrieved 14 March 2015.
- "Privacy and Security: A modern and transparent legal framework". Intelligence and Security Committee of Parliament. 12 March 2015. Retrieved 14 March 2015."UK surveillance 'lacks transparency', ISC report says". BBC. 12 March 2015. Retrieved 14 March 2015."Intelligence and security committee report: the key findings". The Guardian. 12 March 2015. Retrieved 14 March 2015.
- "Handful of UK spies accessed private information inappropriately, ISC says". The Guardian. 12 March 2015. Retrieved 31 December 2016.
- "UK: Unlawful spying on two organisations reinforces need for intelligence services to end mass surveillance". Amnesty International UK. 22 June 2015. Retrieved 31 December 2016.
- "Case No. IPT/13/132-9/H IN THE INVESTIGATORY POWERS TRIBUNAL" (PDF). The Investigatory Powers Tribunal. 26 February 2015. Retrieved 31 December 2016.
- "Legal privilege and the conflicting interests of GCHQ and the IPT". The Guardian. 16 March 2015. Retrieved 31 December 2016.
- "British intelligence service spying on MPs in defiance of laws prohibiting it". The Independent. 23 July 2015. Retrieved 31 December 2016.
- "Daily Hansard - Debate, 15 July 2014 : Column 697". Parliament of the United Kingdom. 15 July 2014. Retrieved 31 December 2016.
- "How Cheltenham entered America's backyard". New Scientist. 5 April 1984. Retrieved 12 December 2014.
- "Benedict Cumberbatch to inspire the next generation of codebreakers". The Observer. 15 November 2014. Retrieved 6 December 2014.
- Aldrich, Richard J. (2010). GCHQ: The Uncensored Story of Britain's Most Secret Intelligence Agency. HarperCollins. ISBN 978-0007278473.
- Johnson, John (1997). The Evolution of British Sigint: 1653–1939. HMSO. ASIN B002ALSXTC.
- Kahn, David (1991). Seizing the Enigma: The Race to Break the German U-Boats Codes, 1939–1943. Houghton Mifflin. ISBN 978-0395427392.
- Smith, Michael (2001). "GC&CS and the First Cold War". In Smith, Michael; Erskine, Ralph. Action This Day: Bletchley Park from the Breaking of the Enigma Code to the Birth of the Modern Computer. Bantam Press. ISBN 978-0593049105.
|Wikimedia Commons has media related to Government Communications Headquarters.|
- Official website
- Her Majesty's Government Communications Centre
- GCHQ: Britain's Most Secret Intelligence Agency
- BBC: A final look at GCHQ's top secret Oakley site in Cheltenham
- INCENSER, or how NSA and GCHQ are tapping internet cables