Baroness Thatcher was taken to hospital late last night for precautionary tests after becoming ill during the evening. She was driven by car from her home in Belgravia, Central London, to St Thomas’ Hospital.

The 82-year-old former Prime Minister has suffered a series of minor strokes in recent years which are said to have left her with a failing memory. In March 2002 she was advised by her doctors to give up public speaking, although she has broken this rule on several occasions.

Those who had met her in recent weeks said that she showed no apparent signs of ill health. However, she has looked increasingly frail on public appearances.

A spokeswoman for the hospital said that Baronees Thatcher was expected to spend the night in hospital for observation.

In a statement, she said: “We can confirm that Baroness Thatcher has been admitted to St Thomas’ Hospital and is expected to remain in hospital overnight for observation.

“Her condition is stable and she is speaking to the medical staff who are caring for her."

A Conservative Party spokeswoman said: “We have been in touch with her office and we wish her well.”

Her health has been in question since as far back as 1994, when she collapsed because of a stomach upset while making a speech in Chile. She was last admitted to hospital in December 2005 after complaining of feeling faint while at her hairdresser’s. She spent the night under observation at Chelsea and Westminster Hospital.

Baroness Thatcher became leader of the Conservatives in 1975 and oversaw sweeping changes during her premiership between 1979 and 1990, advocating free-market economics and cracking down on the trade unions.

She won three general elections and, during her first term in office, sent a naval task force to recover control by force of the Falkland Islands after an invasion by Argentina. She survived a bomb planted by the IRA during the Conservative Party conference in 1984, which killed five people. She was succeeded as the leader of the Tory party by her finance minister, John Major.

Her husband, Denis, died in hospital in June 2003, aged 88.

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