Speaking publicly for the first time since announcing the marriage and following a five-year courtship the 34-year-old prince said: "It's impossible for anybody else to understand why it has taken me so long.

"But I don't think it had been right before and I don't think Sophie would have said yes. Hopefully the fact that she has said yes means I've got the timing right."

The BBC's Jennie Bond reports on the royal match

News of the impending royal wedding was leaked by the Sun newspaper on Wednesday morning and later confirmed by Buckingham Palace.

'No ultimatums'

The paper also claimed Miss Rhys-Jones, 33, had issued the prince with an ultimatum.

The engagement ring was made by the royal jewellers Asprey

But, during a photocall at which she displayed the royal engagement ring, she said: "Contrary to popular opinion we've never lived together and I've never issued any ultimatums."

Prince Edward is the Queen's youngest son but has been a confirmed bachelor for years.

He said: "We are the very best of friends and that's essential but it also helps that we also love each other very much."

The BBC's Jennie Bond looks at the background to the Royal romance

Asked about the possibility of starting his own family, the prince laughed and said: "Let's take one step at a time."

Windsor is favourite

No decision has been made about the date and venue but the couple are hoping to marry at St George's Chapel in Windsor in the late spring or early summer.

The couple said they were both hoping for a slightly low-key wedding.

The bride-to-be said: "Getting married is a very personal thing. Naturally there is going to be more interest in us than in other people but it is a personal matter and a family occasion."

She said it was "slightly nerve-wracking" to join the royal family but she said she was ready.

The couple said it would be "business as usual" and they would be continuing their own careers.

Queen 'delighted'

The Queen is "utterly delighted" with the announcement, which followed a proposal by the prince over the Christmas holidays.

The BBC's David Sillito: "This is going to be quite a low-key wedding"

Ever since Prince Edward and Miss Rhys-Jones began their relationship there have been rumours of an imminent engagement.

News of their relationship was first revealed in December 1993 by Andrew Morton, unofficial biographer of the late Diana Princess of Wales. He wrongly predicted they would get engaged on the prince's 30th birthday in March 1994.

The Sun said Prince Edward hesitated to take the plunge because of he was "painfully aware" of his brothers' failed marriages - Prince Charles's with Princess Diana and Prince Andrew's with Sarah Ferguson.

Low-profile romance

The BBC's Janette Clucas: "Miss Rhys-Jones is already an accepted part of the Royal Family"

Prince Edward has deliberately kept their courtship low profile.

Miss Rhys-Jones has quietly become an accepted part of the royal family and has her own rooms at Buckingham Palace.

Prince Edward and Miss Rhys-Jones will make a thoroughly modern royal couple - both with their own high-flying careers. The prince has his own TV production company, Ardent Productions and last year presented a series called Crown and Country about the history of Britain.

His girlfriend runs her own PR firm and publishes a magazine for the Duke of Edinburgh Awards scheme.

'Wonderful couple'

Her parents, Christopher and Mary, said the prince and their daughter would make a "wonderful couple".

Mr Rhys-Jones said: "We are both extremely pleased and very happy for Sophie and Prince Edward. We have always enjoyed Prince Edward's company and feel that they make a wonderful couple.

"On behalf of our whole family, we wish them every happiness for the future."

The Prime Minister, Tony Blair, was told about the announcement as he prepared to leave the Seychelles for South Africa.

A spokesman said: "He and Cherie are absolutely delighted."

Malcolm Cockren, chairman of the prince's company, Ardent Productions, said the wedding would undoubtedly make a busy year busier but he said they fully supported him.