Royal wedding: Prince William to marry Kate Middleton next year

The second in line to the throne secretly proposed to his long-term girlfriend during a holiday in Kenya last month, giving her Princess Diana's engagement ring.

Prince William said that giving Kate his mother's ring was "my way of making sure my mother didn't miss out on today and the excitement".

He added: "The timing is right now, we are both very, very happy."

Kate said that joining the Royal Family was a "daunting prospect" but added: "Hopefully I'll take it in my stride."

Prince Charles said this afternoon he was thrilled and joked: "They have been practising long enough."

More pictures: Wills and Kate's royal romance

Camilla, the Queen and Prince Philip said they were "delighted" on being told. William asked for permission to marry from Miss Middleton's father Michael, a pilot turned millionaire businessman. Miss Middleton's mother and father were said to be "as excited as any parents can be".

The wedding, possibly at Westminster Abbey, could attract a worldwide TV audience of 2.5 billion.

David Cameron said "a great cheer went up and a great banging of the table" when he told a Cabinet meeting. The Prime Minister, who said he had slept out overnight in The Mall to watch the 1981 wedding of Charles and Diana, said: "It's great to have a piece of unadulterated good news."

It is believed that William proposed to Miss Middleton on the Lewa Downs game reserve that is owned by the family of a former girlfriend of the prince, Jecca Craig.

The couple, both 28, were posing for pictures at St James's Palace this afternoon and recording an interview with Tom Bradby, ITV News political editor, who they have known for some time.

After the wedding they will live in north Wales. William is a flight lieutenant with an RAF search and rescue unit in Anglesey.

William is likely to be offered a dukedom by the Queen, meaning Miss Middleton will become a duchess. She would then become Princess of Wales once Charles becomes king, and eventually Queen Catherine.

A statement from Clarence House said: "The Prince of Wales is delighted to announce the engagement of Prince William to Miss Catherine Middleton."

William and Kate met when both were students and flatmates at St Andrews University in September 2001. Sensible, middle-class Miss Middleton, the eldest of three children, was credited with persuading William to continue his studies when he considered quitting as he struggled to adjust to university life during his first year.

She caught his eye when the prince paid £200 for a front seat at a charity student fashion show to see her stride down the catwalk in a see-through lace dress. They broke up in 2007 but got back together soon after when they attended a concert tribute to Diana on the 10th anniversary of her death.

William once said that he planned to be married by 28. Miss Middleton was dubbed "Waity Katie" as she waited for him to pop the question. At a recent wedding of friends, William was jokingly told it was his turn next.

Speculation now focuses on whether William will follow his parents by getting married at St Paul's Cathedral or whether they will choose a venue such as Westminster Abbey.

If the wedding is held in June this could coincide with William's 29th birthday or the 90th birthday of Prince Philip. There will also be fierce interest in children — Princess Diana became pregnant with William four months after getting married.