They came to honour the longest-serving post-war Prime Minister, whose name still rouses admiration or revulsion, in almost equal measure, 15 years after she was ousted from her office by her own party.
On her arrival she was warmly greeted by the Queen, the pair exhibiting no sign of the froideur said to have marked their relationship during Lady Thatcher's 11-year stint in the highest elected office in the land.
Once the event - a champagne party - got under way, Lady Thatcher was introduced by Lord Carrington, her former foreign secretary, before making a short speech herself. She was given a standing ovation and "Happy Birthday" was sung
The tributes were predictably fulsome from the guests, every one of whom (perhaps even Tony and Cherie Blair) could safely be described as "one of us".
Rupert Murdoch, the media tycoon who developed such a close rapport with her, said: "She is a very important lady."
Tory politicians past and present were equally glowing in their praise. John Redwood said: "It was a wonderful family occasion. There were a lot of people who loved what Margaret did and a lot of people who loved Margaret as a person.
"She was in very good health, in very good form. She spoke extremely well and she spoke generously about all the people who had helped her doing what she did in the 1980s."
Among her admirers in show business, Joan Collins said: "It is a great way to celebrate a great lady who I have absolutely always adored. She is the Iron Lady and I want to be just like that when I grow up."
As he left, the composer Lord Lloyd-Webber declared: "Roll on the 90. She was superb."
In such a large and eclectic crowd, there was plenty of potential for diplomatic incidents.
Mr and Mrs Blair rubbed shoulders with some of the more right-wing Tories. Two Conservative leadership candidates, David Davis and Liam Fox, were there - although notably uninvited were the other two, David Cameron and Kenneth Clarke, Lady Thatcher's Europhile nemesis.
The Queen perhaps tried to avoid contact with Lady Thatcher's son, Mark, now a convicted felon, and Jeffrey Archer, another Thatcher acolyte, who attended with his wife, Mary. Also there was Prince Mangosuthu Buthelezi, the leader of South Africa's Inkatha Freedom Party.
Lady Thatcher has rarely appeared in public since the death of her husband, Denis, in 2003. She gave up public speaking on her doctor's advice after suffering a series of small strokes.
The guest list
The principal guests at last night's reception to mark the 80th birthday of Baroness Thatcher were:
HM The Queen & HRH The Duke of Edinburgh, HRH The Princess Alexandra, Lady Ogilvy, Sir Anthony & Lady Acland, Lord Alliance, Mr & Mrs David Amess, Mr & Mrs Anthony Andrews, Mr Richard Anelay & Lady Anelay, Lord & Lady Armstrong, Lord & Lady Baker, Sir Anthony & Lady Bamford, Dame Shirley Bassey, Lord & Lady Bell, Lord Belstead, Lord & Lady Biffen, Mark Birley, Sir Michael Bishop, Lord & Lady Blackwell, The Prime Minister & Mrs Tony Blair, Mr & Mrs John Bolton, Lord & Lady Bramall, Lord & Lady Brightman, Tony Britton, Lord & Lady Broers, Lord & Lady Brooke, Vice Admiral Sir James & Lady Burnell-Nugent, Prince Mangosuthu Buthelezi, Lord & Lady Butler, Lord & Lady Carrington, Mr & Mrs William Cash, Mr & Mrs John Caudwell, The Bishop of London & Mrs Chartres, Mr & Mrs Christopher Chope, Sir George & Lady Christie, Mr & Mrs Jeremy Clarkson, Joan Collins, Lord & Lady Cope of Berkeley, President & Mrs Cossiga, Jim Davidson, Mr & Mrs David Davis, General Sir Peter & Lady De La Billiere, Lord Deedes, Mr Alan Duncan, Mr & Mrs Iain Duncan Smith, Mr Michael Thomas & Lady Dunn, Lord & Lady Fellowes, Lord & Lady Ferrers, Frank Field, The Hon Lady Forte, Mr & Mrs Eric Forth, The Rt Hon Lord & Lady Forsyth, Mr & Mrs Frederick Forsyth, Lord & Lady Fowler, Dr Liam Fox & Dr Jesme Baird, Lady Getty, The Lady Annabel Goldsmith, Sir Donald Gosling, Lord & Lady Gowrie, Rt Hon & Mrs John Gummer, Kathy Gyngell, Mrs William Hague, Lord & Lady Hamilton of Epsom, Lord & Lady Harris of High Cross, Lord & Lady Harris of Peckham, David Heathcoat-Amory, The Hon Mrs Drue Heinz, Lord & Lady Hesketh, Rachael Heyhoe Flint, HE Mr & Mrs Robert (Holmes) Tuttle, Mr & Mrs Michael Howard, Mr & Mrs Gerald Howarth, Lord & Lady Howell, Sir Rex & Lady Hunt, General Sir Mike & Lady Jackson, The Baroness James of Holland Park, Lord & Lady Jellicoe, Mr & Mrs Bernard Jenkin, Lord & Lady Jenkin, Sara Jones, Lord & Lady Jopling, Lady Joseph, Lord & Lady Kalms, Lord & Lady Kelvedon, Lord & Lady King, Lord & Lady Kingsdown, Lord & Lady Laing, Lord Lamont, Lord & Lady Lawson, Sir Mark & Lady Lennox-Boyd, Mr & Mrs Oliver Letwin, Mr & Mrs Peter Lilley, The Earl of Lichfield, Lord & Lady Lloyd-Webber, Lord & Lady Lothian, Lord Luce, Lord Lyle, Lord & Lady Macgregor, Lord & Lady Mackay, The Rt Hon Sir John Major & Dame Norma Major, The Duke & Duchess of Marlborough, Lord & Lady Mawhinney, Lord & Lady Mayhew, Lord & Lady McAlpine, Sir Trevor McDonald, The Duke & Duchess of Montrose, Mr & Mrs Charles Moore, Lord & Lady Moore, Mr & Mrs Rupert Murdoch, Mr & Mrs Pete Murray, Mr & Mrs Boris Nemtsov, Lord & Lady Newton, Mr & Mrs Michael Noakes, The Duke & Duchess of Norfolk, Sir John & Lady Nott, Sir Gus & Lady O'Donnell, Lord & Lady Palumbo, Lord & Lady Parkinson, Mrs Michael Portillo, Mrs Pam Powell, Mr & Mrs Robert Powell, Lord & Lady Powell, Jonathan Powell, John Profumo, John Redwood & Nikki Page, Lord & Lady Rees-Mogg, Sir Tim Rice, Lady Ridley, Andrew Rosindell, Mr & Mrs David Ross, The Duke & Duchess of Rutland, Her Grace The Dowager Duchess of Rutland, Lord & Lady Ryder, Mrs Charles Saatchi, Lord & Lady Saatchi, Lord & Lady Salisbury, Mr & Mrs Hugh Scully, Mr & Mrs Nelson Shanks, Mr William Shawcross & Ms Olga Polizzi, Sir David & Lady Sieff, Admiral Sir Jock & Lady Slater, Sir Michael & Lady Spicer, Sir John & Lady Stanley, Tomasz Starzewski, Lord & Lady Sterling, Lord & Lady Stoddart, Mr & Mrs Richard Stone, Mr & Mrs Norman Stone, Lord Strathclyde, Mr & Mrs David Tang, Lord & Lady Tebbit, Lord & Lady Thomas, Dame Sue Tinson, Lady Trumpington, Sir Andrew & Lady Turnbull, Mr & Mrs Shailesh Vara, Lord & Lady Waddington, Lord & Lady Wakeham, Lord & Lady Waldegrave, Sir Alan & Lady Walters, Lord & Lady Weatherill, Lord & Lady Weidenfeld, The Hon Caspar & Mrs Weinberger, Mr & Mrs Guy Weston, Stuart Wheeler, Mr & Mrs Marco Pierre White, June Whitfield, The Lady Whitelaw, Mr & Mrs John Whittingdale, Mr & Mrs Terry Wogan, Lord & Lady Wolfson of Marylebone, Lord & Lady Wolfson of Sunningdale, Admiral Sir John & Lady Woodward, Sir Robert & Lady Worcester, Sir David & Lady Wright, Sir Oliver & Lady Wright, Sir Jimmy & Lady Young.Reuse content