Sir Jonathan Stephen Day, CBE (born 23 April 1954) is a retired British Civil Servant lately serving as the Chairman of the Joint Intelligence Committee and Head of the Joint Intelligence Organisation at the Cabinet Office.
Day initially trained as a solicitor, and joined the Civil Service in 1979. During his career, Day worked in the Ministry of Defence, the Foreign & Commonwealth Office and the Cabinet Office, was seconded to NATO, and did a year's sabbatical at Harvard University. Day retired at the end of November 2015, and was replaced by Charles Farr as Chair of the JIC.
Day was appointed Commander of the Order of the British Empire (CBE) in the 1999 New Year Honours for his contribution to the Strategic Defence Review as Director of Defence Policy at the MoD and was knighted in the 2016 New Year Honours.
| Director-General, Security Policy
Ministry of Defence
as Director-General, Security Policy & Operations
| Second Permanent Secretary
Ministry of Defence
Sir Alex Allan
| Chair of the
Joint Intelligence Committee
- Ex-pupil's top post with MoD – This is Gloucestershire
- NATO Who's who?: Director Private Office – Jon Day (2001)
- Day, Jon (2012). "DAY, Jonathan Stephen". Who's Who 2012, online edition. A & C Black. Retrieved 5 March 2012.
- "New Chair for the Joint Intelligence Committee". Cabinet Office. 2012-03-02. Retrieved 5 March 2012.
- "Joint Intelligence Committee Chair appointed: Charles Farr – Press releases – GOV.UK". www.gov.uk. Retrieved 2015-12-13.
- "Second Permanent Under Secretary — Jon Day". Ministry of Defence. 2011. Retrieved 5 March 2012.
- "No. 55354". The London Gazette (Supplement). 30 December 1998. p. 7.
- "No. 61450". The London Gazette (Supplement). 30 December 2015. p. N2.
- "New Year's Honours 2016 list" (pdf). GOV.UK. 30 December 2015. Retrieved 30 December 2015.
- "Organogram and staff pay data for Ministry of Defence — Central TLB Senior staff, as of September 2011". Ministry of Defence. September 2011. Retrieved 5 March 2012.