LONDON - Crowds camped out in London and foreign dignitaries flew in from around the world for Friday's wedding of Prince William and Kate Middleton, a marriage full of pomp and ceremony that has thrust the monarchy to centre stage.

Recalling William's mother, Princess Diana, who was killed in a car crash in Paris in 1997, the couple have chosen to lead the hymns with the final hymn that was sung at her funeral in Westminster Abbey where the couple will marry.

Middleton, 29, attended a final rehearsal on Thursday at the abbey, the coronation church for the monarchy since William the Conqueror was crowned in 1066, accompanied by William's younger brother and best man Prince Harry.

In a message of thanks to well-wishers worldwide, the couple said they were deeply touched by the outpouring of affection ahead of a wedding service that will combine ancient traditions of the monarchy with a sense of modernity to reflect the times.

In the service, Middleton will not promise to "obey" William as part of her wedding vows in front of a congregation gathering royals, politicians, celebrities and friends.

"We are both so delighted that you are able to join us in celebrating what we hope will be one of the happiest days of our lives," William, the second in line to the throne, and Kate wrote in a statement printed in an official souvenir programme.   

DIANA CONSPICUOUS BY ABSENCE

Diana's friend Elton John, who sang "Candle in the Wind" at her funeral, will be a guest on Friday and William has given Kate his mother's dazzling sapphire and diamond engagement ring.

The royals' cool reaction to Diana's death contrasted starkly with a huge outpouring of public grief and marked a low point for the monarchy.

William's marriage to Middleton, who is from an affluent middle-class background rather than the aristocracy, is seen as adding a renewed dash of glamour to a faded brand and several commentators have compared her to Diana.

On the street across from the abbey, some 200 people had already set up a makeshift campsite, with tents draped in British "Union Jack" flags, pictures of the couple and banners reading "It's cold but worth it" and "It could have been me".  "I'm a romance novelist so I had to come for the most romantic event in the world," said Sheree Zielke, 55, who has travelled from Canada to watch the event which has been met by republicans with indifference and by royalists with excitement.

WORLD HUNGERS FOR ROYALS

Outside Britain though, the world's fascination with the British royal family is undiminished. An estimated 8,000 journalists have arrived in London to cover the ceremony, and hundreds of millions across the world will watch on television.

Part of that interest stems from the memory Diana commands, particularly in the United States.

William, now 28, was 15 when the hugely popular Diana was killed. William and his brother Harry walked behind their mother's cortege at her funeral.

Diana's death and scandals involving other members of the royal family saw support for the House of Windsor dive in the 1990s but their approval ratings are now much improved.

Three-quarters of those polled by Ipsos MORI for Reuters on the wedding last week said they favoured Britain remaining a monarchy.

Such has been the reversal of their fortunes that there was little opposition when Charles married his long-term lover Camilla in 2005, a marriage that was thought inconceivable less than a decade earlier due to Diana's public standing.

Middleton, whose parents run a successful business while her mother's family is descended from miners, will be the first commoner to marry a monarch-to-be since Anne Hyde wed the future James II in the 17th century.

Commentators say this is bound to help the royals' image of being able to adapt and modernise.

"Their marriage will breathe new life into the monarchy as the queen enters the twilight of her reign, bringing new blood and a fresh perspective to an institution that faces criticism for being elitist and out of touch," royal biographer Claudia Joseph told Reuters.

Details of the wedding service released on Thursday showed the music would have a largely British theme and will include Welsh hymns illustrating the couple's connection to Wales. William's father Prince Charles, the future king, is the Prince of Wales and the wedding ring will be made from Welsh gold.