Jonathan "Jon" Stephen Day, CBE (born 23 April 1954) is a British Civil Servant currently 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. Day has worked in the Ministry of Defence, the Foreign & Commonwealth Office and the Cabinet Office, and has been seconded to NATO and done a year's sabbatical at Harvard University. He was awarded a CBE in 1998 for his contribution to the Strategic Defence Review as Director of Defence Policy.