Prince William and Kate Middleton have named the day - Friday, April 29, next year at Westminster Abbey.
St James's Palace said their wedding - including the costs of the church service, music, flowers, decorations reception and honeymoon - would be paid for by the Royal family and the Middleton family. The public will pay for associated costs like security.
Jamie Lowther-Pinkerton, private secretary to Prince William, said the couple chose Westminster Abbey for its "staggering beauty", 1,000-year Royal history and intimacy despite its size.
He told reporters in a briefing at St James's Palace: "The venue has long associations with the Royal family - it is in many ways the Royal family's church - and of course with Prince William personally."
The abbey was also the venue of William's mother's funeral. As a 15-year-old boy the Prince walked behind the coffin of Diana, Princess of Wales as it was led to the imposing church in September 1997.
Mr Lowther-Pinkerton said those planning the nuptials were very conscious of Britain's precarious finances: "All parties involved in the wedding, not least Prince William and Miss Middleton, want to ensure that a balance is struck between an enjoyable day and the current economic situation."
Mr Lowther-Pinkerton said William and Miss Middleton were "completely over the moon" about their engagement: "I've never seen two happier people, which is absolutely fabulous to work in that sort of environment."
"They're now getting stuck into organising their wedding. They are very much in charge of the arrangements for the big day. They're giving us and the Household office very firm direction indeed."
Mr Lowther-Pinkerton added: "We know that the world will be watching on April 29, and the couple are very very keen indeed that the spectacle should be a classic example of what Britain does best."
William has requested that as far as possible members of the armed forces involved in the wedding should be drawn from those already on ceremonial duties to ensure personnel are not taken off operations or training.
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