LONDON – The Prince of Wales is to marry Camilla Parker Bowles in a civil ceremony on April 8 followed by a church blessing at Windsor Castle, it was announced yesterday.

Mrs. Parker Bowles will become Her Royal Highness Duchess of Cornwall.

The announcement ends years of speculation about when, or if, the couple, who first met more than 30 years ago, would marry. It was made seven-and-a-half years after the death of Diana, Princess of Wales.

The Queen gave her official permission immediately after consulting Prime Minister Blair at her weekly audience with him on Wednesday, officials said.

Questions remain over Mrs. Parker Bowles’s title on the prince’s accession to the throne. Clarence House said she would then assume the title HRH Princess Consort, an unprecedented title modeled on the prince consort title bestowed on Queen Victoria’s husband, Prince Albert.

Convention dictates that any wife of a king is entitled queen consort, but senior aides have acknowledged that legislation may be required in the future if she is not automatically to assume the title.

The wedding announcement was made sooner than planned after details were leaked to the press.

The prince discussed the matter with the Queen and with Sir Michael Peat, his private secretary, at Christmas, when the date was settled.

The prime minister was alerted on Friday that the Queen would, in accordance with the Royal Marriages Act, be formally consulting him on the matter, and had intended to make a formal announcement next week.

The prince, 56, has given Mrs. Parker Bowles, 57, an engagement ring described as a family heirloom.

He said in a statement: “Mrs. Parker Bowles and I are absolutely delighted. It will be a very special day for us and our families.”

Besieged by the press on an official visit to the Goldsmiths’ Company in Central London, where, appropriately, he was shown engagement rings, he said he was “very excited.”

The couple appeared at a charity gala at Windsor Castle Wednesday night when Mrs. Parker Bowles said she was “just coming down to earth.”

She disclosed that the prince had gone down on one knee to propose. “Of course,” she said. “What else?”

She smiled broadly and showed her engagement ring: platinum with a square-cut central diamond and three diamond baguettes on either side.

She wore a deep fuchsia jersey dress by Jean Muir, pearl choker, and pearl earrings.

Aides said the couple had “considered the issue of marriage” for a long time and “both felt the time was ripe.” The Queen welcomed the news by instructing that the round tower at the castle should be illuminated last night. In a short statement, she said: “The Duke of Edinburgh and I are very happy that the Prince of Wales and Mrs. Parker Bowles are to marry. We have given them our warmest good wishes for their future together.”

Princes William and Harry were said to be “100%” behind their father.

In a statement, they said: “We are both very happy for our father and Camilla and we wish them all the luck in their future.”

Mr. Blair informed the Cabinet at its morning meeting. Later, he said: “I am delighted for the Prince of Wales and Camilla Parker Bowles. It is very happy news and when Cabinet heard it, they sent congratulations and good wishes on behalf of the whole government.”

Earl Spencer, the brother of Diana, Princess of Wales, refused to comment.

In keeping with Church of England guidelines on divorced couples remarrying, a registrar will conduct a civil ceremony at Windsor.

The Archbishop of Canterbury, Rowan Williams, has been closely involved and said he was pleased that the couple had decided to take “this important step.”

He said: “I hope and pray that it will prove a source of comfort and strength to them and to those who are closest to them.”

Mr. Williams will preside at the service of prayer and dedication after the civil ceremony.

He said: “These arrangements have my strong support and are consistent with Church of England guidelines concerning remarriage, which the Prince of Wales fully accepts as a committed Anglican and as prospective Supreme Governor of the Church of England.”

Guests will be “largely friends and family,” and aides are looking into the possibility of televising some of the ceremony, if not all. The couple will spend their honeymoon at Birkhall, the house on the Balmoral estate that the prince inherited from the late Queen Mother.

After the wedding, Mrs. Parker Bowles would, legally, become the Princess of Wales, which is the title assumed by the wife of the heir to the throne. But aides said she had chosen not to use it.

“She would like people to use Duchess of Cornwall. Her reasons are private.” Her Royal Highness Duchess of Cornwall is one of many titles automatically bestowed on the wife of the heir to the throne, as is the Duchess of Rothesay, the title used in Scotland. An aide said: “They have discussed it between them and they felt it would be nice if she was called Princess Consort. It is a nice title. They feel it is appropriate. They feel it is right.”

Officials said that, as far as Clarence House was aware, “there is no Act of Parliament that says the wife of the king should be called the queen. Obviously, it has been convention in the past, but these are new times.” It was “not a burning issue.”

Downing Street confirmed that no legislation was “needed at this stage” to prevent Mrs. Parker Bowles from becoming queen. But House of Commons sources said the view was being formed that an Act would be needed to prevent Mrs. Parker Bowles from becoming queen, to ensure that by default she did not benefit from the Civil List.

With the situation as it is and the prince’s accession potentially many years away, a groundswell of public support could lead to Mrs. Parker Bowles assuming the title of queen.

As Duchess of Cornwall, she will become the most senior female member of the Royal Family after the Queen. She will have no constitutional role but will be included in state and national occasions at the Queen’s invitation. Whether she will wear a tiara will also be a matter for the Queen.

She will join the prince on engagements and tours and perhaps add to the charities she supports. But she is likely to tread slowly immediately after the wedding.

An aide said: “She will catch her breath, let things settle down, and ease herself into it.”