Succession

Wikipedia: Succession to the British Throne

Wikipedia: Act of Settlement 1701

Wikipedia: Statute of Westminster 1931

Former Prime Minister Gordon Brown proposed changing the Act of Settlement 1701 so that the succession to the Throne was no longer discriminatory by religion or gender: Gordon Brown in talks to end ban on Catholics joining royal family

Since the Statute of Westminster 1931, agreement on changes to the rules for succession would need to be approved by all the Commonwealth Realms. There is a precedent where such agreement has been sought and naturally granted. That was for the abdication from the throne of King Edward VIII in 1936: His Majesty’s Declaration of Abdication Act 1936