Proof that the lady was once for turning

The lady was not for turning. However, private papers released today show that an early U-turn executed by Margaret Thatcher changed the course of modern British history.

The former prime minister was so upset at being turned down for the parliamentary seat of Orpington in 1955 that she told Conservative Central Office she was quitting politics for a career in the law.

She wrote in January 1955: "The only political temptation left for the next 10 years was Orpington for which I have long had an affinity. Now that temptation has been removed for all time I shall continue at the Bar with no further thought of a parliamentary career for many years."

Her letter was greeted with dismay at Central Office where she had been spotted as one of the party's rising stars. One note in her candidate's file referred to her as "quite outstanding in her ability" with "a most attractive personality and appearance".

But a year later she wrote back to say that she did after all want to become an MP, to express her "strong views". Within three years, she was the MP for Finchley.

The letters are among papers released by the Archives Centre at Churchill College, Cambridge, where all the Thatcher papers are held. It is the first time that papers from a prime minister's private archive have been opened to the public during their lifetime.

The majority of the documents, from Baroness Thatcher's time in office, remain closed as they are covered by the 30-year rule on the release of government documents.