Downing Street has drawn up plans to end the 300-year-old exclusion of Catholics from the throne. The requirement that the succession automatically pass to a male would also be reformed, making it possible for a first born daughter of Prince William to become his heir.
The proposals also include limiting the powers of the privy council, in particular its role as arbiter in disputes between Scotland or Wales and the UK government.
The plans were drafted by Chris Bryant, the MP who was charged by Gordon Brown with reviewing the constitution. They are with the prime minister’s new adviser on the constitution, Wilf Stevenson.
Sources said No 10 would like the legislation to be passed quickly in a fourth term and Bryant briefed constitutional pressure groups on the plans at a private seminar in Manchester this week.
Ministers have long thought it anomalous that it is unlawful for a Catholic to be monarch but have not had the political will to risk reforming the law.
The 1688 Bill of Rights , the Act of Settlement in 1701 and Act of Union in 1707 – reinforced by the provisions of the Coronation Oath Act 1688 – effectively excluded Catholics or their spouses from the succession and provided for the Protestant succession.
Neither Catholics nor those who marry them nor those born to them out of wedlock may be in the line of succession.
The law also requires the monarch on accession to make before parliament a declaration rejecting Catholicism.
Though the Act of Settlement remains a cornerstone of the British constitution, critics have long argued about its relevance in the 21st century, saying it institutionalises religious discrimination and male primogeniture.
The Coronation Oath Act requires the monarch to “maintaine the Laws of God the true profession of the Gospel and the Protestant reformed religion established by law […] and […] preserve unto the bishops and clergy of this realm and to the churches committed to their charge all such rights and privileges as by law do or shall appertain unto them or any of them”.
Any change in legislation would, among other things, require the consent of member nations of the Commonwealth.
Constitutional experts have argued that reform of the Act of Settlement and its related statutes would set in train an inevitable momentum towards disestablishment, and disestablishing the Church of England would automatically remove the rationale for the religious provisions binding succession to the crown.