Former Tory Prime Minister Baroness Thatcher has celebrated her 80th birthday with the Queen and 650 guests at a dinner in a London hotel.
Lady Thatcher looked frail as she arrived 15 minutes late - aides said she had been delayed by talking on the phone to US President George Bush.
But she re-emerged later to welcome the Queen and later defied doctors' orders by speaking at the event.
Lady Thatcher was ousted from her post in 1990, after 11 years at No 10.
The dinner was attended by Lady Thatcher's twin children Carol and Sir Mark.
It saw a toast proposed by Lord Carrington, who resigned as her foreign secretary over Argentina's invasion of the Falklands.
Lady Thatcher replied - despite being advised months ago by doctors that she should not make public speeches in the wake of some minor strokes.
Ex-Cabinet minister Lord Parkinson said: "She to everybody's surprise made a speech and was also very witty and entertaining and we were just pleased to see her in such good shape."
Another ex-minister, John Redwood, said: "She spoke extremely well and she spoke generously about all the people who had helped her doing what she did in the 1980s."
The Queen rarely attends personal celebrations of serving or former prime ministers.
But she rubbed shoulders with current Labour Prime Minister Tony Blair and show business stars at the dinner in the Mandarin Oriental Hotel in Hyde Park.
Scores of politicians joined the woman once dubbed the Iron Lady, including current Conservative leader Michael Howard and her immediate successor Sir John Major.
Mr Howard said the UK had been on its knees in 1979.
"The bulk of the credit for the turnaround that has taken place since then belongs to her," said the outgoing Tory leader.
As well as ex-Cabinet ministers such as Nigel Lawson, disgraced Tory peer Jeffrey Archer is also at the event.
Among the stars of stage and screen invited were composer Andrew Lloyd-Webber, singer Shirley Bassey, comedian Jim Davidson and actress Joan Collins.
Saying she had always adored Lady Thatcher, Ms Collins said: "She is the Iron Lady and I want to be just like that when I grow up."
Of the four contenders for the Tory leadership, only two have been invited, David Davis and Liam Fox.
Dr Fox said Lady Thatcher was a "great historic figure" and suggested the Tories did not need to distance themselves from her record.
Baroness Thatcher served as prime minister between 1979 and 1990
"You always have to move forward but only someone with little appreciation of just what she had contributed would be willing to pass aside a figure as monumental as Margaret Thatcher.
"Self-loathing should not be part of the Tory tradition."
David Cameron was not invited as Lady Thatcher did not know him, nor was Ken Clarke, with whom she had had differences.
And Lord Heseltine, who famously challenged Lady Thatcher's leadership, was not invited to the party.
Liberal Democrat leader Charles Kennedy was also not on the guest list.
Lady Thatcher has arranged to meet former Soviet leader Mikhail Gorbachev, and Henry Kissinger, who was US Secretary of State in the era of President Richard Nixon at meetings in London next week as part of the birthday celebrations.
Guests at the dinner paid tribute to her political legacy.
Tory Lords Leader Lord Strathclyde said: "Margaret Thatcher herself represents far more than just an individual.
"She represents something that has changed the world for the better."
Former Cabinet secretary Lord Butler said Lady Thatcher had been "one of the great prime ministers" - but he did not think she still had an influence on politics.