Gordon Brown has declared his intention to overhaul the monarchy by abolishing the 308-year-old law that bans heirs to the throne from marrying Roman Catholics.
It could open the way to disestablishing the Church of England which is why many atheists are pushing for the change.
Mr Brown also signalled that he wishes to change the rule of ‘primogeniture’, where sons of the monarch automatically precede their older sisters in the line of succession.
The suggestions will be discussed with the Heads of Government at the Commonwealth Summit this weekend.
The 1701 Act of Settlement currently bans members of the Royal Family from either converting to Roman Catholicism or marrying a Roman Catholic, unless they agree to be removed from the order of succession.
Earlier this year Evan Harris, an atheist and Liberal Democrat MP, tabled a Private Members Bill calling for an end to the ban on heirs to the throne marrying Roman Catholics, and proposed to end ‘primogeniture’.
Last night Mr Harris urged the Prime Minister to consult the Commonwealth Heads of Government “so that we can get rid of this discriminatory symbol at the heart of our constitution”.
Mr Brown responded saying that “most people recognise the need for change.”
Critics have attacked the plans.
A group of senior MPs including Ann Widdecombe, a Roman Catholic, warned that Britain’s identity as a Christian nation could be endangered by amending the Act.
This is because amending the Act could open the way to disestablishing the Church of England.
Currently the monarch is the Supreme Governor of the Church of England and the “Defender of the faith”.
There are concerns that the proposed changes to the Act of Settlement are the latest move in a campaign to make Britain a secular state.
Many Roman Catholics say the Act of Settlement is not a particular concern to them.
While Shadow Justice Secretary Dominic Grieve attacked the reforms saying: “With the country stuck in recession, our troops engaged in Afghanistan and our prisons in crisis, the Government should have more pressing matters to deal with.”
Past attempts to change the Act of Settlement have been controversial, because it could affect the established status of the Church of England.