wedding dress

As the couple disclosed that they had secretly become engaged during a romantic break in Kenya last month, Miss Middleton showed off the sapphire and diamond ring which the Prince had hidden in his rucksack until he proposed.

“It’s very special to me, and Kate is very special to me now as well, so it’s only right the two are put together,” the Prince said.

“It’s my way of making sure my mother didn’t miss out on today and the excitement and the fact that we’re going to spend the rest of our lives together.”

Miss Middleton described the proposal as “very romantic” and admitted that joining the Royal family was a “daunting prospect”.

The Prince of Wales announced the couple’s engagement in a statement from Clarence House at 11.08 yesterday morning.

It was such a closely guarded secret that the only other person who knew about it was Miss Middleton’s father, Michael, who had given his permission when the Prince asked for his daughter’s hand in marriage when the couple returned from Africa.

In keeping with an 18th century law, the Prince also had to ask the Queen’s permission, but only did so during a phone call yesterday morning.

The Prince of Wales and Miss Middleton’s brother and sister were told little more than three hours before the announcement was made public.

Prince Harry, who also learned the news yesterday, said: “I am delighted that my brother has popped the question. It means I get a sister, which I have always wanted.”

Asked why he had taken so many years to propose, the Prince said: “I didn’t realise it was a race … but the time is right now, we’re both very, very happy and I’m very glad that I have done it.”

Miss Middleton said: “We have been going out for a long time now and … it just seemed the natural step for both of us”.

Sources close to the Royal family said the engagement ring, given to Diana, Princess of Wales by the Prince of Wales when they became engaged in February 1981, fitted Miss Middleton perfectly without needing to be adjusted.

The couple said they had already discussed having children, and Miss Middleton said: “I hope we will be able to have a happy family”.

The Queen and the Duke of Edinburgh were “absolutely delighted for them both”, a Buckingham Palace spokesman said but the Queen and the Prince of Wales remarked on the couple’s delay in getting engaged.

Asked for his personal reaction to the news, the Prince of Wales joked: “Thrilled – they have been practising for long enough!”

During a reception at Windsor Castle for leaders of British overseas territories yesterday, the Queen told one guest: “It is brilliant news. It has taken them a very long time.”

Although no venue has yet been decided, Royal sources said the couple, who are both 28, will choose between Westminster Abbey and St Paul’s Cathedral.

The Prince, whose parents were married at St Paul’s, is said to favour Westminster Abbey, where the Queen and the Duke of Edinburgh were married and where his mother’s funeral was held. He is also said to want the ceremony to be more “low key” than previous royal weddings.

Although bookies made July an even-money favourite for the month of the ceremony a potential clash with the marriage of Prince Albert of Monaco on July 9 means April or May are strong possibilities.

David Cameron was among the first to speak to the Prince to offer his congratulations. The Prime Minister was handed a piece of paper informing him about the engagement during the morning’s Cabinet meeting, and said ministers gave a “great cheer” and banged the table when he broke the news.

The Archbishop of Canterbury, Dr Rowan Williams, who is expected to conduct the service, expressed his “delight” at the engagement announcement.

The couple’s first marital home will be the cottage on Anglesey which the Prince has been renting for several months near RAF Valley, where he is beginning a three-year tour of duty as a search and rescue helicopter pilot.

Miss Middleton, who will be known as Queen Catherine when her fiancé eventually becomes King, will receive her first title on her wedding day.

The Prince is expected to be given a dukedom, with possible titles including Duke of Clarence or Duke of Cambridge, meaning Miss Middleton would become a duchess.

Asked about the prospect of becoming Queen, Miss Middleton said: “It’s quite a daunting prospect but hopefully I’ll take it in my stride, and William’s a great teacher so hopefully he’ll be able to help me along the way.

“I’m really looking forward to spending my time with William.”

The Prince replied: “She’s very good at flattery.”

He described the couple’s relationship by saying: “Obviously we both have a very fun time together, both have a very good sense of humour about things, we’re down to earth, we take the mickey out of each other a lot, and she’s got plenty of habits that make me laugh that I tease her about.”

Miss Middleton added: “Over the years William has looked after me, he’s treated me very well, as the loving boyfriend he is, he is very supportive of me through the good times and also through the bad times.”

Sources said the couple had been discussing marriage for “two or three years” and had delayed the announcement following the death of Miss Middleton’s grandfather, Peter Middleton, whose funeral was last week.