PRINCE William is to marry his long term girlfriend Kate Middleton next year, Clarence House has announced.

The pair became engaged during a holiday in Kenya last month. William gave Kate his mother Diana's engagement ring, a sapphire surrounded by diamonds.

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

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

"The wedding will take place in the Spring or Summer of 2011, in London. Further details about the wedding day will be announced in due course.

"Prince William and Miss Middleton became engaged in October during a private holiday in Kenya.

"Prince William has informed The Queen and other close members of his family. Prince William has also sought the permission of Miss Middleton's father.

"Following the marriage, the couple will live in north Wales, where Prince William will continue to serve with the Royal Air Force. "

The couple have been together since meeting at St Andrews university. But it hasn't all been plain sailing, with William's move to Dorset blamed for a temporary split in 2007.

Speaking from Poundbury this afternoon, Prince Charles said he was "thrilled",adding: "They have been practising long enough."

Speaking at his Poundbury model village in Dorset, the Prince joked: "They have been practising long enough."

When congratulated by a member of the public, he said: "It makes me feel very old. Thank you very much."

His sentiments were shared by Miss Middleton's father Michael and mother Carole. Mr Middleton said: "I would just like to say that Carole and I are absolutely delighted by today's announcement and thrilled at the prospect of a wedding some time next year.

"As you know Catherine and Prince William have been going out together for quite a number of years which has been great for us because we have got to know William very well.

"We all think he is wonderful and we are extremely fond of him. They make a lovely couple, they are great fun to be with, and we've had a lot of laughs together.

The Duchess of Cornwall added that news of Prince William's engagement was "absolutely wonderful".

The Queen and the Duke of Edinburgh are "absolutely delighted", Buckingham Palace said.

The Queen held a reception this afternoon at Windsor Castle for leaders of British overseas territories including Bermuda, Montserrat and the Falklands Islands. One of the guests congratulated the Queen on William and Kate's engagement, to which she replied: "It is brilliant news. It has taken them a very long time."

But there have already been calls from campaigners to make sure that the taxpayer does not end up footing the bill for the wedding. Security costs alone could run into millions, experts said.