Ministers will be warned that they are running out of time to end discrimination against Roman Catholics and women in the rules on who can succeed to the throne. Communications have been opened between Gordon Brown and Buckingham Palace on moves to scrap a centuries-old bar on royal heirs marrying Catholics. The Prime Minister is said to present changes to the 1701 Act of Settlement, which also gives precedence to male heirs, to Commonwealth heads of government at a meeting in November. But Liberal Democrat MP Evan Harris said his Private Member's Bill, which will be debated by the Commons, was the Government's last chance to act on the issue before the next General Election. He said: "There is nothing new in the Government saying they want to see change since when first elected 12 years ago they said they would end unjustified discrimination wherever it exists. "But there has been no action to back that up. If they want to get rid of the historic anti-Catholic marriage rules and male chauvinist rules of succession, then they need to support this Bill, amend it as necessary and make sure it passes." He added: "They can't wait until next year because our constitution also tells us that their time is up in June. This is the last chance." The Act of Settlement states that heirs to the throne lose their right to be sovereign if they marry a Catholic or convert - forcing Catholic royal brides over the years to leave that faith to protect their husband's birthright. The wife of Peter Phillips, the Queen's grandson, did just this before their wedding last year so that he remained 11th in line to the throne.