Charles and Camilla to marry on 8 April

Legislation required to enact the marriage of the Prince of Wales to Camilla Parker Bowles will be seized upon by MPs determined to question the future role of the monarchy, it emerged yesterday after the couple announced their wedding plans. A Bill settling the new constitutional arrangement is expected to be debated in Parliament to give the couple's wedding on 8 April full legal status.

Legislation required to enact the marriage of the Prince of Wales to Camilla Parker Bowles will be seized upon by MPs determined to question the future role of the monarchy, it emerged yesterday after the couple announced their wedding plans. A Bill settling the new constitutional arrangement is expected to be debated in Parliament to give the couple's wedding on 8 April full legal status.

Charles and Camilla made their first public appearance as fiancés at a dinner at Windsor Castle last night. With a large diamond and platinum engagement ring on her finger, Camilla said she was "just coming down to earth" after the proposal.

The announcement came 34 years after the two first met at a polo match at the castle. Camilla married Andrew Parker Bowles in 1973, but remained close to the Prince after he married Diana Spencer in 1980.

According to her biographer, Andrew Morton, Diana was jealous of Camilla from the start. Around the time of her divorce, she said there were "three people" in the marriage, although the affair between Charles and Camilla was not public knowledge until the revelation of the "Camillagate" tapes in 1992.

Camilla divorced in 1995, and after Charles's divorce and the death of Diana, she emerged gradually, although she did not meet Princes William and Harry until 1999 ­ two years after Diana's death.

Although pro-republican MPs have signalled that they do not intend to oppose the marriage, they will want to use any debate on the constitution to bring public scrutiny to the rising costs of the Royal Family.

MPs may press for amendments to the Bill that could include proposals for reducing the Civil List, the taxpayers' contribution to maintaining the Queen and her close family. Others may want to see a new constitutional settlement that gives women and non-Anglicans equal rights to the throne.

House of Commons sources said yesterday that, without legislation, Mrs Parker Bowles may inadvertently benefit from the complex Civil List provisions. Earlier this week, it emerged that Prince Charles, 56, paid himself £11.9m last year out of his private wealth, the historic estates of the Duchy of Cornwall.

Mrs Parker Bowles, 57, receives a personal allowance of £130,000 a year from the Duchy to cover her living costs. But her claim on Prince Charles's vast wealth will have already been settled by what one lawyer described yesterday "as one of the biggest pre-nuptial contracts" ever signed. Prince Charles will be mindful of the £17m settlement he finally agreed with the lawyers of his first wife.

Part of the new arrangements will consider a £2m life insurance policy in which Mrs Parker Bowles is sole beneficiary. Under the terms of this insurance trust set up by Prince Charles, Mrs Parker Bowles is provided with an income of around £150,000 a year. She cannot get at the capital which, at her death, would revert to William and Harry.

Last night, MPs, often critical of the Royal Family, were keeping their powder dry for the expected debate. Alan Williams, the Labour MP who earlier this week, in an attack on Prince Charles's finances, said "he wins the national lottery every year", declined to comment.

After her marriage, Camilla Parker Bowles will become the most senior female royal after the Queen. But she will not be known as the Princess of Wales, a title which for many still conjures up memories of Diana, killed in 1997. The new Bill will give Camilla the title HRH Duchess of Cornwall, which grants her precedence within the Royal Family as wife of the heir to the throne.

But, unlike her sister-in-law the Princess Royal, her importance relies solely on marriage. She will have no constitutional role, but will attend state and national occasions at the Queen's invitation. When Charles becomes King, she will be known as Princess Consort, a title similar to that last commonly used by Queen Victoria to describe Prince Albert.

For the Church of England remarriage after divorce is a vexed question, and, as King, Charles would become its supreme governor. A breakthrough came in July 2002 when the General Synod cleared the way for divorcees to marry in church. However, continued resistance among bishops may explain why the couple are not having a church wedding, but plan to be married in a civil service.