Gabb joined the Libertarian Alliance in 1979. He graduated in History from the University of York in 1982. In 1998 he gained a PhD in Political and Intellectual History from the University of Middlesex. He became the Director of the Libertarian Alliance in 2006, shortly before the death of its founder Chris Tame.
In 1991 and 1992 he was the Economic and Political Adviser to Jan Carnogursky, the Prime Minister of Slovakia where he was attacked for being a free market radical. He was a director of the Sudan Foundation which existed "to promote better relations between the British and Sudanese peoples". He resigned from this post in January 1999.
 Political writing
Gabb has written on a number of conservative leaning websites including vdare and lewrockwell.com. He has also written for newspapers such as The Times and the Birmingham Post. He also wrote an obituary for Chris Tame.
 Political positions
Gabb is for the legalization of drugs and is an opponent of multiculturalism and mass immigration as a political policy. He sees no harm in gay marriage or gay adoption, but defends the need to be able to speak in open criticism of homosexuality as part of his stance for freedom of speech from political interference. He is an isolationist in foreign affairs (he is as much anti-American as Eurosceptic) and an advocate of the widest social and economic liberty. He has written in support of the monarchy and House of Lords, in defence of the rights of holocaust deniers and in enabling a time limitation law on the charge of child abuse.
Gabb is controversial to some because of his views, for example: "the Commission for Racial Equality and all similar organisations should be abolished, and their records burned." Gabb explained this by often likening the British government to a police state, saying, "Every so often, someone stands up and tells us what benefits we have had from diversity. Such may be, but we must also consider that part of the price has been a police state. In this country, we have severe restrictions on freedom of speech, on freedom of association and on freedom of contract - all in the name of good race relations." He compared the government to a police state as far back as 1989, when he wrote, "The Thatcher Government has brought into being the full coercive apparatus of a police state."
Regarding freedom of speech, Gabb has written: "It is no business of the State to tell people what they can and cannot think. Our bodies are our own. Our minds are our own. What we do with them is our business." He has also said that the government "should cut benefits, taxes and regulation, and leave people alone. The people will do the rest." Gabb is against the European Union. He has said of immigration: "I do not necessarily object if people want to come to this country to look for a new life. I do object if they want this at my expense - at my expense as a tax payer, and at the expense of the constitutional rights which are my birthright."
In favor of free markets, Gabb has taken a position against limited liability corporations on that basis that they shield shareholders from their debt obligations, representing a state subsidy. He said in an Oxfam debate that their creation was "one of the greatest legislative mistakes of the 19th century. Their existence is based on a separation of ownership from control. The owners are released from all responsibility."
On 2 December 2011, he issued a press release calling for the repeal of all drink-drive legislation. The mother[who?] of a child road accident victim responded by text, "I think I would have preferred the drunk to have been stopped before he killed my 12yo son, rather than after". However, Gabb is on record as saying that although anybody should be able legally to drive under the influence of any substance whatever, the legal penalties for then actually causing harm to third parties should be exemplary.
 Yasmin Alibhai Brown
The Libertarian Alliance did a press release stating that Gabb had been invited to take part in a talk taped for the BBC on multi-culturalism, debating with Yasmin Alibhai-Brown. Alibhai-Brown objected when Gabb said that the Libertarian Alliance believed the government's Commission for Racial Equality should be shut down, saying that without laws meant to control discrimination, it would occur more frequently. Gabb asked her, "Yasmin, are you saying that the indigenous majority in this country is so seething with hatred and discontent that it is only restrained by law from rising up and tearing all the ethnic minorities to pieces?" To which Alibhai-Brown answered, "Yes." Gabb asked if Alibhai-Brown seriously thought that Gabb wanted to murder her, at which point Gabb's voice was faded out, 20 minutes prior to the end of the debate. After this debate, it was alleged by the Libertarian Alliance that Gabb's microphone was shut off.
From 1999 to 2001, Gabb kept a website called the "Candidlist," which named UK Members of Parliament who held Europhile views. According to London's Evening Standard, after MP Ian Bruce was named on the site, Bruce emailed Gabb: "I hope you are very rich. Would you please let me both have a note of your postal address and where you would like me to serve court papers on you." After Bruce demanded, "Action this day... I will campaign tirelessly to retain the pound," Gabb wrote back, "I will make this reclassification before I go to bed tonight."
In 2006, Gabb published a novel, The Column of Phocas, under his own imprint, "Hampden Press". This was republished in 2008 by Hodder & Stoughton under the name "Richard Blake", and retitled Conspiracies of Rome. Three more novels in the same series have been published by Hodder & Stoughton under the name Richard Blake: The Terror of Constantinople (2009), The Blood of Alexandria (2010), and The Sword of Damascus (2011).
Under his own name, Gabb has published The Churchill Memorandum (2011).
 Partial bibliography
- Cultural Revolution, Culture War: How Conservatives Lost England and how to Get It Back, The Hampden Press, London, 2007.
- The Column of Phocas (historical novel), The Hampden Press, London, 2006.
- Trusting Brands in Society: The Quality and Value of Modern Medicine, Centre for the New Europe, Brussels, 2005.
- Smoking, Class, and the Legitimation of Power, The Hampden Press, London, 2005.
- From Antitrust to Disaster: An Overview of European Union Competition Policy, Centre for the New Europe, Brussels, 2004.
- The Cost of European Environmental Regulations in the Accession Countries of Central and Eastern Europe, Centre for the New Europe, Brussels, 2004.
- Why Greater Freedom of Patient Information in European Healthcare Could Save Lives and Money, Centre for the New Europe, Brussels, 2004.
- War and the National Interest: Arguments for a British Foreign Policy, The Hampden Press, London, 2004.
- (With Dennis O'Keeffe) Markets, the Internet, and Morality, The Institute of Economic Affairs, London, 2003.
- Why Trade Barriers between the European Union and the Developing World Should be Lowered, Centre for the New Europe, Brussels, 2003.
- Dispatches from a Dying Country: Reflections on Modern England, The Hampden Press, London, 2001.
- (With Dennis O'Keeffe and Pat Stoll (eds)) Issues in School Attendance and Truancy, Pitman Press, London, 1995.
- (With Dennis O'Keeffe) The Report of the North London Truancy Unit, Her Majesty's Stationery Office, London, 1994.
- "Officers and Advisory Council of the Libertarian Alliance". The Libertarian Alliance.
- "Alumni" (PDF). Grapevine (Spring 08): 21. 2008. Retrieved 2008-12-25.
- "Slovak Writings". Sean Gabb. 1992-06-30. Retrieved 2010-11-13.
- Sean Gabb. "Reply to Mimochodom, an Article by Zuzana Szatmary". Seangabb.co.uk. Retrieved 2010-11-13.
- "Free Life 30, May 1999". Seangabb.co.uk. 2005-09-01. Retrieved 2010-11-13.
- "Sean Gabb Articles". VDARE.com. Retrieved 2010-11-13.
- "Mark Oaten, Rent Boys and the Secret Police: A View of How England Is Governed at the End of Its History by Sean Gabb". Lewrockwell.com. 2006-01-24. Retrieved 2010-11-13.
- "Should the Church be disestablished Yes says Dr Sean Gabb". The Times (London). 2008-10-24.
- "Why all true citizens need their own guns - Life & Leisure". Birmingham Post. 2006-06-07. Retrieved 2010-11-13.
- "Chris R. Tame". The Independent (London). 2006-03-23.
- Sean Gabb, Culural Revolution, Culture War, August 2007
- Sean Gabb, Culural Revolution, Culture War, The Homophobic Heresy, August 2007
- Arguments for a British Foreign Policy, Daniel P. Mulroney, igreens.org.uk, 2004
- Why Libertarians Should Sing "God Save the Queen", Sean Gabb, Free Life Commentary, 7 September 1997
- Why the Hereditary Peers Should Stay in the House of Lords, Sean Gabb, Free Life Commentary, 25 November 1998
- Dr Sean Gabb (2007-04-24). "Defending the Right to Deny the Holocaust, Sean Gabb, 24 April 2007". Seangabb.co.uk. Retrieved 2010-11-13.
- Reflections on the Gary Glitter Case, Sean Gabb, Free Life Commentary, 14 November 1999
- "The Right, the Left and 'Free Expression'". Whatnextjournal.co.uk. Retrieved 2010-11-13.
- "BBC Censors Discussion of Multiculturalism: Shuts off Microphones on Libertarian Alliance Spokesman". The Libertarian Alliance. 2004-02-16. Retrieved 2007-09-17.
- "The Full Coercive Apparatus of a Police State: Thoughts on the Dark Side of the Thatcher Decade". Libertarian Alliance. 1989-05-03. Retrieved 2007-09-17.
- "Be fair to all parents". The Evening Standard. 2007-07-11. Retrieved 2007-09-17.
- "Free Trade v Fair Trade". Free Life Commentary. 2005-04-16. Retrieved 2007-09-17.
- "If we want to reduce the number of deaths on the roads, drinking and driving should not in itself be a crime. It should be possible for a person to drink a bottle of whisky, get into a car and drive away - and the authorities should have no power to stop this. Punishment should only come if a driver is so erratic that he is plainly dangerous - or if an accident is caused. But it should then in this latter case be very severe punishment. In general, we believe in real punishments for real crimes. Unless a real crime can be shown, we believe in telling the police to mind their own business." LA News Release: Scrap All Drinking and Driving Laws, Friday the 2nd December 2011
- Cambridge University Conservative Association Yasmin Alibhai-Brown: racist.
- "BBC World Service debate on Multi-culturalism". Retrieved 2010-11-13.
- "Correspondence between Sean Gabb and Ian Bruce MP". Retrieved 2012-03-07.