A group of Labour backbenchers in the House of Lords is tabling proposals to give females equal rights with males to inherit land and titles. They plan to force a parliamentary debate on the issue in the next few weeks.
Although the proposals are not officially sponsored by the Government, they have won the support of Baroness Jay, the Leader of the Lords, who believes that the principle of primogeniture - the right of the elder son automatically to inherit a title - is outdated.
The Government is planning its own measures to reform the hereditary peerage in the longer term. Ministers have already promised to change the law to give Royal daughters equal rights to succeed to the throne.
The move, which coincides with the crucial committee stage of the Lords reform Bill this week, will further infuriate hereditary peers. It is likely to fuel their determination to resist the Government's attempt to throw all but 91 of them out of the Upper Chamber.
But Labour peers believe that change to the way in which peerages are handed down is long overdue and want to raise the issue as part of the Government's agenda of constitutional reform. Baroness Gould said: "The principle of equality should apply across the board and it should be the eldest child who inherits the title, not only the eldest son."
Baroness Thornton said: "The current situation is saying that girls are somehow valued as less than boys and it is impossible to justify that kind of discrimination in the modern world."
Their proposals are similar to those in Lord Archer of Weston-super- Mare's Primogeniture Bill, which sought to give Royal daughters equal rights to succeed to the throne. The Tory peer agreed to drop his measure after the Government said it planned to bring forward its own legislation implementing the change. The Queen let it be known that she would be happy for the plan to go ahead.
Lord Archer said he would be delighted for his proposals on equality to be applied more broadly. But Lord Strathclyde, leader of the Tory peers, said hereditary peers would fiercely resist the change. "Either the Labour Party is in favour of the hereditary principle or it is not. If it is not it should not mess around with it and if it does take the hereditary peers seriously then it should not remove them from the Lords."
Conservative peers are planning legal action if the Government forces its legislation on the Lords by using the Parliament Act. They have been legally advised that they could challenge the Act in the courts.
If the law is changed, an obvious beneficiary would be Tamara, eldest daughter of the Duke of Westminster, who has a younger brother. A major loser would be Louis, only son of Earl Spencer.