John Reid, the former Home Secretary, last night urged Gordon Brown to include a proposal to change or even scrap the 307-year-old Act of Settlement in Labour's next election manifesto.

The MP for Airdrie and Shotts was responding to The Herald's exclusive report yesterday in which Jim Murphy, the Scottish Secretary, revealed that the UK Government was "working hard" on ways of amending or even abolishing a cornerstone of the British constitution, which bans Roman Catholics from becoming king or queen and prevents the monarch from marrying a Catholic.

Mr Reid, a Catholic, said: "I very much welcome the confirmation by the Scottish Secretary that the government are looking at ways to change or repeal the discriminatory aspects of the Act of Settlement.

"There is now widespread recognition that this needs to be done and I hope that the government can confirm, before the next election, that this will be part of our manifesto commitment."

Mr Murphy, also a Catholic, expressed his desire to see a change in the law and wanted progress to be made before the next election. He said: "It's unfair, wrong, discriminatory and does not fit well into a modern sense of what Britain is about."

Jack Straw, the Justice Secretary in charge of constitutional matters, is leading the behind-the-scenes work on the Act.

Changing the law will be strongly resisted in some political and religious circles as it would have major constitutional repercussions. It would not only involve the sovereign as Supreme Governor of the Church of England but also the Anglican community across the world. Opening up the monarchy to a Catholic could, in theory, ultimately lead to the disestablishment of the Church of England.

Last night, shadow justice secretary Nick Herbert said: "At a time of serious economic downturn, I believe the public would be amazed if the government was giving any priority at all to amending a 300-year-old constitutional settlement, particularly when to do so would presumably have no impact until, at the very earliest, the death of the next monarch but one."

Click here to comment on this story...