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Sir Jonathan Stephen Day (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. Provided by Wikipedia