What's it like to be a Prime Minister's bodyguard?

John Warwicker served three Prime Ministers for almost six years at Downing Street in the late seventies and has written a book about the experience.

He told Today: "I certainly wouldn't recommend it. The job description is appalling. The hours are totally anti-social. The rewards are relatively modest, the criticism enormous. Everyone enters happily and ends in tears".

Mr Warwicker said Margaret Thatcher was the best professional to work with. He said: "She entered with very little knowledge but she was a quick learner and unusually for a Prime Minister she was prepared to listen to those people who were her subordinates, such as me, but who had a specialist aptitude to offer".