Alex Allan was appointed head of the Joint Intelligence Committee (JIC) last November.
At the time, he was permanent secretary at the Ministry of Justice.
He has spent most of his professional life in the Civil Service, joining from Cambridge University in 1973 after schooling at Harrow.
He is seen as something of an eccentric, and, lacking a background in intelligence, was a slightly unusual choice for the role.
His selection may have been prompted in part by the desire to distance the JIC from its recent difficulties.
The committee was at the centre of the political storm over its 2003 dossier on Iraq's weapons of mass destruction.
On his appointment, headlines referred to his interest in the Grateful Dead, a 1960s Californian counter-culture band.
Mr Allan runs a website for fans of the group, known as Deadheads.
His website lists the band's records and fan trivia and says his hobbies are windsurfing and cycling.
During a train strike in the 1980s he windsurfed to work down the Thames wearing his work suit and a bowler hat and carrying a briefcase and umbrella.
The stunt backfired when he fell in the river near Big Ben.
After working for the Customs and Excise department on joining the Civil Service, Mr Allan moved to the Treasury, and was principal private secretary to Nigel Lawson when he was chancellor.
He was High Commissioner in Australia for two years from 1997 and was principal private secretary to John Major in Downing Street.
Tony Blair made him his e-envoy, with the task of improving internet use in the Civil Service.
The job of JIC chairman carries a reported £185,000 salary.