The public has never been afforded such a detailed account of MI5, the national security agency, as it was by Mrs Rimington in the 1994 Richard Dimbleby lecture.
Mrs Rimington, appointed head of the Security Service in 1991 - the first woman and the first to be publicly identified - denied any incompatibility between the work of MI5 and the defence of parliamentary democracy. 'It is the right of the individual to participate freely and safely in our democracy that we are here to protect,' she said.
There have been allegations that MI5 has been politically partisan, that it has targeted trade unions and left- wing activists, and that some officers conspired to subvert Harold Wilson's government in the 1960s. Mrs Rimington said: 'It is difficult for an organisation which must work in secret to talk about what it does and to satisfy its critics. One result is the tendency for completely untrue 'conspiracy theories' to emerge . . . One of the most persistent (was) that MI5 plotted to undermine the then prime minister, Harold Wilson. No such plot existed.'
She dismissed suggestions that the service targeted high- profile people - possibly a reference to allegations that MI5 recorded telephone conversations between the Prince of Wales and Camilla Parker- Bowles. 'I and my staff believe deeply that the very serious step of intruding into people's private lives must be strictly limited to what is unavoidable in the interests of national security.'
The focus of MI5 had changed since its foundation in 1909. Its main work was no longer to catch foreign spies, and there had been a decline in the amount of work connected with 'subversion' at home.
'Since the collapse of Soviet communism, the threats to national security have changed greatly. Countering espionage now takes up less than a quarter of our resources; half what it was three years ago, and a far cry from the position at the height of the Cold War,' she said.
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