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.
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, through her, her immediate 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 pounds 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 pounds 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 protracted pounds 17m divorce settlement he finally agreed with the lawyers of his first wife, the late Diana, Princess of Wales.
The couple's lawyers will have also redrawn both their wills to take account of the new constitutional position.
Part of the new arrangements will consider a pounds 2m life insurance policy in which Mrs Parker Bowles is the sole beneficiary.
Under the terms of this insurance trust set up by Prince Charles, Mrs Parker Bowles is provided with an income of around pounds 150,000 a year.
She cannot get at the capital which, at her death, would revert to Charles's sons, William and Harry.
Last night, MPs, often critical of the Royal Family, were keeping their powder dry for the expected parliamentary 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 people all over the world still conjures up memories of Diana, who was killed in a car crash in Paris in 1997.
The new Bill will give Camilla the title HRH Duchess of Cornwall, which grants her precedence within the Royal Family as the wife of the Prince of Wales and heir to the throne.
But unlike her sister-in-law, the Princess Royal, her importance solely relies upon marriage. She will have no constitutional role, but will be invited to state and national occasions at the Queen's invitation.
When Charles becomes King, she will be known as Princess Consort, a title similar to the one last commonly used by Queen Victoria to describe her beloved Prince Albert.
Yesterday's announcement could only have been secured with the combined support of the Queen, the Prime Minister and the Archbishop of Canterbury.
The Church represented the biggest obstacle. After all, for the Church of England remarriage after divorce is a vexed question, and, as King, Charles would become the Anglican Church's supreme governor.
A breakthrough came in July 2002 when, in an historic vote, the General Synod cleared the way for divorcees to marry in church.
The Church's governing body recognised there were exceptional circumstances in which a divorced person may be married in church during the lifetime of a former spouse.
However, continued resistance among senior Church of England bishops may explain why the couple, who have known each other for 30 years, are not having a church wedding, but instead plan to be married during a civil service at Windsor Castle.