The Act of Settlement (1701) laid down that only Protestant heirs of Princess Sophia, granddaughter of James I, may succeed to the British throne. Neither Roman Catholics, nor those who marry a Roman Catholic, nor those born out of wedlock, may remain in the line of succession. Under common law the crown was passed on by male primogeniture under which younger sons succeed before their elder sisters.
This changed on the 26 March 2015 with the introduction of the Succession to the Crown Bill 2013 which changed the succession laws so that the right of male primogeniture no longer applies. Males born after 20 October 2011 no longer precede their elder sisters in the line of succession. The Duke and Duchess of Cambridge’s first child born on 22 July 2013 was a boy Prince George. Their second child Princess Charlotte was born on 2 May 2015. She is 4th in line and will not lose her position even if she has a younger brother.
The Bill removed the disqualification of those who marry Roman Catholics so that George Windsor, Earl of St Andrews, who married a Catholic in 1988 was restored in 35th place after the Duke of Kent. It also repealed the Royal Marriages Act 1772 so that only the first 6 persons in line to the throne require the Sovereign’s approval to marry. This means that Princess Beatrice and Princess Eugenie no longer require permission from the Queen to marry.
The British monarch is head of the Protestant Church of England so the requirement remains that only Protestants can be in the line of succession.
British Throne – Line of Succession
The current line of succession to the British Throne is given below.