A first-born daughter of Prince William and Kate Middleton would accede to the throne under constitutional changes being considered by the British government.
The Coalition is reported to be negotiating with Australian and other Commonwealth governments about changes to a 309-year-old Act so that female royals would enjoy equal succession rights as their brothers.
It would be a considerable break from royal tradition and the wheels turn slowly in such affairs.
For it to go ahead, there would need to be legislation altered in each of the 15 Commonwealth countries that have the Queen as head of state.
British Prime Minister David Cameron is expected to discuss changes to the 1701 Act of Settlement at a summit of Commonwealth leaders from October 28-30 in Perth.
Former PM Gordon Brown started work on amending the Act that also forbids Roman Catholics from taking the crown.
Britain's Constitutional Affairs Minister Mark Harper said Cameron's government, that came to office last May, had continued that work.
"Ministers have already accepted that the provisions of the Act of Settlement might be discriminatory. Discussions are under way," he said in The Daily Telegraph.
But he added it was not a "straightforward process" and could take years to complete.
Labour MP Keith Vaz introduced a bill to the House of Commons this week proposing changes to the rules of succession.
It will be debated in May.
Prince William will marry Ms Middleton on April 29 at Westminster Abbey.
