She defends MI5's activities during the miners' dispute on the grounds it was directed by a "triumvirate who had declared that they were using the strike to try to bring down the elected government and it was actively supported by the Communist party".
The three leaders of the National Union of Mineworkers at the time were Arthur Scargill, the president, Mick McGahey, the vice-president, and Peter Heathfield, the general secretary.
The first official admission that MI5 was involved in the miners' strike comes in the latest extract of her memoirs, Open Secret, published exclusively in the Guardian.
Dame Stella, who headed MI5's counter-subversion branch at the time, says accusations that the agency was "running agents or telephone interceptions to get advance warning of picket movements are wrong".
"We in MI5," she says, "limited our investigations to the activities of those who were using the strike for subversive purposes."
She defends MI5's targeting of leading CND activists on the grounds that the anti-nuclear movement, which she calls "entirely legitimate", was "of great interest to the Soviet Union" which encouraged the Communist Party of Great Britain to infiltrate it.
Dame Stella's decision to go into print in the face of fierce opposition from the Whitehall establishment was defended yesterday by MI5's former legal adviser, David Bickford. He backed her calls for a radical reform of the Official Secrets Act, saying Britain's security and intelligence agencies were living in the "sailing ship age".
Live debate
Read what the Guardian's Richard Norton-Taylor said about Stella Rimington's explosive memoir
Interactive quiz
Could you be a spy?
