Baroness Thatcher has died aged 87 following a stroke, it has been announced.

The former prime minister, who had suffered bouts of illness for many years, was said to have died peacefully.

Her spokesman, Lord Bell, said: "It is with great sadness that Mark and Carol Thatcher announced that their mother, Baroness Thatcher, died peacefully following a stroke this morning. A further statement will be made later."

Buckingham Palace said: "The Queen is sad to hear the news of the death of Baroness Thatcher and Her Majesty will be sending a private message of sympathy to the family."

In a statement on the Downing Street Twitter feed, David Cameron said: "It was with great sadness that l learned of Lady Thatcher's death. We've lost a great leader, a great Prime Minister and a great Briton."

Lady Thatcher earned a place in the history books as the first woman prime minister when she entered Downing Street in 1979.

Over the next 11 years even her critics admitted that she changed the face of the country.

In recent years her health deteriorated, and she stopped making public appearances.

Lady Thatcher suffered several small strokes in 2002, and received medical advice against accepting any more public speaking engagements.

Her increasingly frail condition when she was seen - especially after the death of husband Denis in 2003 - led to frequent bouts of speculation about her health.

But MPs and friends who saw her regularly said she remained alert and interested in politics, and she was not known to have deteriorated notably recently.

There have been calls for the ex-premier to receive a state funeral, although she was a divisive figure for many on the Left.

Mr Cameron will return home early from Spain this afternoon, a Downing Street spokesman said. He had been in the country for talks with EU leaders.