A Scottish Nationalist MSP has added further weight to appeals from both civic and religious groups for the UK government to end the long-standing ban on a Roman Catholic becoming king or queen.
Christine Grahame made the call to Prime Minister Gordon Brown after documents obtained by her under the Freedom of Information Act showed that the late first minister Donald Dewar, a highly respected figure in Scotland and beyond, thought the ban was "no longer acceptable".
The problem goes back to the 308-year-old Act of Settlement, which prevents Catholics from becoming the monarch. It is buttressed by the position of the Church of England as Established under the Crown - a matter which has also elicited renewed calls for reform and an end to the formal church-state tie.
Ms Grahame, who represents the South of Scotland at the Holyrood Scottish parliament, denounced the UK Government for its "utterly indefensible position" in not amending the law.
"Labour ministers are fully aware that this discriminatory legislation has no place in a modern democracy," she declared. "It is simply not good enough for British ministers to hide behind the smokescreen they have laid down, claiming the subject too complex to interfere with. That is neither a credible, acceptable nor tenable position to sustain."
In his memo, the late Mr Dewar said the act "reflects the political concerns of an earlier era and it is also based on a kind of prejudice which is no longer acceptable in modern society."
He acknowledged the constitutional difficulty of a change, but said it should be tackled.
Liberal Democrat MP Evan Harris has also called for reform, as have the Catholic Church and a number of senior constitutional lawyers.