The guest-list, though containing a scattering of politicians and foreign dignitaries, will reflect the Princess's own life, and will be based as much on the views of the Spencer family and her own private office as those of Buckingham Palace.
Among celebrities from the world of pop music, her friend Elton John will be attending the Westminster Abbey service, where it is thought he will sing. Other pop stars expected are George Michael and Sting, with his wife, Trudi Styler. From a different generation, the Welsh-born singer Shirley Bassey is likely to attend.
Although Saturday's ceremony will not rival designer Gianni Versace's service for sheer volume of fashion glitterati - an event attended by Diana herself - leading figures from that world will be represented. These may include include the models Cindy Crawford and Iman, wife of David Bowie. The designer Catherine Walker is also certain to be invited, as is Liz Tilberis, editor of Harper's Bazaar magazine. The Italian fashion designer Valentino will also attend.
Other celebrities likely to be asked will include the businessman Richard Branson, Anna Harvey, the deputy editor of Vogue magazine, the actor John Travolta, the dancer Wayne Sleep and the photographer Mario Testino, who took portraits of the Princess for Vanity Fair - and which Diana considered her favourite.
Her friend Jemima Khan and her husband, the former Pakistan cricket captain Imran Khan will be present, as will Jemima's mother, Lady Annabel Goldsmith, and Diana's Brazilian friend Lucia Flecha de Lima. Near the top of the list will be Rosa Monckton, one of Diana's closest friends, with whom she shared a holiday in Greece two weeks ago.
Among charity friends will be the Rev Tony Lloyd, executive director of The Leprosy Mission, Mike Whitlam, director-general of the British Red Cross and Derek Bodell, of the National Aids Trust.
The Palace has not sent out the usual endless invitations to ambassadors in black suits and there has been a deliberate attempt to avoid a dignitary- driven ceremony. However, there will be representatives from other countries, including Hillary Clinton, wife of the US President, and Bernadette Chirac, wife of the French President.
Among British politicians Plaid Cymru is to be represented, and Sir Edward Heath, Lord Callaghan and Baroness Thatcher were confirmed on the list, with John Major. Cabinet members attending include Mr Blair, John Prescott, Robin Cook, the Foreign Secretary and Lord Irvine, the Lord Chancellor. It is expected Mr Blair, with Cherie Booth, will visit Balmoral on Sunday before going on to reopen the campaign for Scottish devolution.
The form of the 45-minute service has not been finalised, though it is believed Verdi's Requiem, one of Diana's favourite pieces of classical music, will be played. The organising committee's challenge is to plan a dignified and traditional service which also fits the modern image of the "People's Princess".
William Beaver, the Church of England's head of communications, stressed: "The decisions are still being made. It is a religious occasion and it is a sensitive occasion, but we want it to be one in which everyone can share."
One of the Princess's showbusiness friends, the singer Luciano Pavarotti, has said he was asked to sing - but was too grief-stricken to accept.Reuse content