Succession was largely governed by male-preference cognatic primogeniture , under which sons inherit before daughters , and elder children inherit before younger ones of the same gender . The Prime Minister of the United Kingdom , David Cameron , announced at the Commonwealth Heads of Government Meeting 2011 that all 16 Commonwealth realms , including the United Kingdom , had agreed to abolish the gender-preference rule for anyone born after the date of the meeting , 28 October 2011 . They also agreed that future monarchs would no longer be prohibited from marrying a Roman Catholic – a law which dated from the Act of Settlement 1701 . However , since the monarch is also the Supreme Governor of the Church of England , the law which prohibits a Roman Catholic from acceding to the throne remains . The necessary UK legislation making the changes received the royal assent on 25 April 2013 and was brought into force in March 2015 after the equivalent legislation was approved in all the other Commonwealth realms
Commonwealth Heads of Government Meeting 2011
Commonwealth Heads of Government Meeting 2011
Monarchy of the United Kingdom