The gay wedding of the year: Elton and David tie the knot

It is the must-have celebrity invite of the year and the most eagerly awaited of the "gay marriages" which have been made possible by the new civil partnership laws. But it also marks the first time a man who has been married to a woman will legally marry another man.

Not that the fact will be of much concern to Sir Elton John - who was married to Renate Blauel for three years during the mid-1980s - and his long-term partner, David Furnish, when they legally tie the knot this morning at the Windsor Guildhall. It is the same register office where the Prince of Wales and Camilla Parker Bowles were married earlier this year and the same registrar, Claire Williams, will conduct the ceremony.

The morning will be deliberately low key with only the parents of both men attending.

The real glitz comes in the evening when 700 guests including Liz Hurley and Victoria Beckham - her husband will be detained by Real Madrid - Donatella Versace, various Osbournes, Graham Norton and the likes of Rod Stewart and Lulu, who may well perform, will gather in a vast marquee in the grounds of Sir Elton's home to guzzle pink champagne and dance the night away. Although it was designed to be a low-key "soirée" for about 50 people, the party has mushroomed into a major event, the style of which can be best judged by the fact that one of the organisers is Peregrine Armstrong Jones, the party planner who is said to have put Victoria and David Beckham on twin thrones for their nuptials several years ago.

The cost is believed to be well over £1m, which includes a small fortune spent on Sir Elton's favourite lilies. Shepherd's pie, the original choice for an ironic main dish, has been dropped as too proletarian and replaced with roast lamb. However, the dress code is said be "restrained" with the emphasis on black ties and smart gowns and none of the wigs and Regency costumes sported by Sir Elton and Mr Furnish at his 50th birthday party.

Kim Mnguni, of Blonstein & Associates, one of London's major party and event organisers said the occasion would be "camp". She said: "It has to be, it's going to be, camp. It's going to be fantastic, of course. The logistics of 700 people in a marquee is not that big for such a party but it is the most prestigious event around. And security will be a nightmare, probably the most difficult part of it.'' The cost, she said, was impossible to estimate: "Who knows - it's maybe one, two or even three million.'' Sir Elton is even paying for the policing.

None of that is likely to be recouped by way of diamond encrusted toasters as wedding presents from the celebrity guests. Sir Elton, as a man who can already afford most things, has stipulated that donations should be made instead to his Aids charity.

Sir Elton, 58, and Mr Furnish, 43, warmed up for today's partying with a "hen" night at the Too2Much gay bar in Soho, London, on Monday night.

While today's event is certainly a celebration of one relationship, it is also the most visible demonstration of the new era in weddings made possible by the Civil Partnerships Act, which gives gay and lesbian couples the same legal rights as heterosexuals.

The first of more than 1,000 scheduled ceremonies can take place in England and Wales today, which followed Northern Ireland on Monday and Scotland yesterday. Some registrars in the deeply religious Western Isles have refused to conduct ceremonies, although they were legally obliged to record the marriage.

Guide to the big day

THE CEREMONY

Low key and official in the morning at Windsor Guildhall, with only the parents of both men in attendance. Expect lots of curious onlookers, the world's media and the odd placard-carrying protester.

THE PARTY

A vast marquee, seating 700 guests in the grounds of Sir Elton and Mr Furnish's mansion, Woodside, near Windsor. Lots of sparkly decoration and abundant lilies, but likely to be sophisticated and elegant .

THE GUESTS

The great and the good of modern celebritydom. Everyone from Liz Hurley to the artist Sam Taylor-Wood and, allegedly, Elizabeth Taylor, flown in at Sir Elton's request and expense. George Michael, who has reportedly patched up his feud with Sir Elton, may also show up, as one of many high-profile gay attendees.

THE FROCKS

Sir Elton has requested a restrained dress code, so expect Oscars-night style glamour with no more than the normal amounts of bare flesh on display. Ozzy Osbourne will be wearing his normal black.

THE FOOD AND DRINK

Roast lamb and Christmas chocolate log, say the reports. But you can assume it won't be quite that simple. Canapés to die for and as much pink champers as you can drink are the order of the day.

THE ENTERTAINMENT

Will Sir Elton take to the stage? We think not, but you never know. Much more likely is Lulu and possibly some other attendees delivering a few love songs. Standard wedding reception stuff, in other words.

THE PRESENTS

Since Sir Elton has requested donations to his Aids charity, the opportunity for a little present-giving one-upmanship has been lost. But it's hard to believe someone won't be tempted to give an ironic set of salad servers - gold ones, of course.

THE HONEYMOON

David Furnish is reportedly planning to whisk his new husband away somewhere quiet. They'll need it after today.