I've never been one to retreat at the first whiff of gunshot

Stella Rimington

In an interview with The Guardian, she said the absolute duty of confidentiality which the Official Secrets Act imposed on former members of the security and intelligence services was "unrealistic".

Dame Stella said it should be made easier for former members to write about their work, and she called for an independent review body to vet publications.

She also revealed MI5 tried to stop her publishing her book, Open Secret, but said she never intended to betray secrets or embarrass the service.

The Guardian's editor, Alan Rusbridger, said it was a very frank account of her role as the first woman in charge of MI5, but did not contain anything startling.

Cold war

Describing how she was urged not to publish, Dame Stella said it was "quite upsetting because suddenly you go from being an insider to being an outsider and that's quite a shock".

But she added: "I've never been one to retreat at the first whiff of gunshot."

Dame Stella said MI5 bosses were "ridiculously careful" about the contents of the book, telling her to remove any mention of the SAS, even when describing the well-documented killing of three unarmed IRA members by SAS soldiers in Gibraltar in 1988.

Oleg Gordievsky said the book would encourage others to divulge secrets

She also admitted MI5 was over enthusiastic during the cold war, with files opened on people not actively threatening the state.

She also gave the first official confirmation that during general elections MI5 checked prospective MPs to see if "there is anything in there of importance ... so the prime minister can take it into account when he forms his government".

Former KGB defector Oleg Gordievsky said the book was an act of "treachery" which would assist anyone who wanted to penetrate the British secret service.

He told BBC Radio 4's Today programme: "The more they know about the details, how the services are organised, the easier it is to penetrate. Such a book by the head of the security service is a gift."

The former defence secretary, Lord King, also criticised her decision to go ahead with the book.

The implication that comes out of some of this, is that somehow there doesn't need to be secrets any more.

Lord King

He said: "I've made clear already I thought it was a mistake, I think she shouldn't have done it. Because it is the signal that she sets.

"The real danger here is, and the implication that comes out of some of this, is that somehow there doesn't need to be secrets any more, the Cold War's over and can't we just have full and frank exposure of everything.

But Mr Rusbridger told the BBC the fuss over the book was unnecessary.

He said: "There is a ludicrous culture of secrecy in this country about these kinds of things.

Alan Rusbridger: Book a 'fantastic advert' for secret service

"When the book is published it will be seen a fantastic advertisement for the security services.

"Privately they realised that but they felt they had to go through the motions of kicking up this fuss."

Mr Rusbridger said her book is an account of the transformation of MI5 from a rather clubby, boozy, male-only establishment to the organisation it is today.

"It's actually a very personal book about her own life. Her marriages, her divorce, her children and how she struggled to keep that on the road at the same time as her job," he said.