By Michael Holden
LONDON (Reuters) - King Charles III succeeded his mother Queen Elizabeth II on the British throne after her death on Sept. 8 last year, becoming king of not just the United Kingdom, but also Australia, Canada, New Zealand and 11 other countries.
Here are brief details of the rules of succession for the British monarch:
WHO IS NEXT?
Under the British constitution, a sovereign succeeds to the throne the moment his or her predecessor dies, before being proclaimed to the people, so there is no interregnum.
The rules, most of which date back hundreds of years, mean the crown passes to the monarch's eldest child, and the line is then dictated by birth order and closeness to the existing sovereign.
So, Charles' eldest son Prince William is the heir to the throne, followed by William's eldest son Prince George, and then his younger children Charlotte and Louis.
Prince Harry, Charles' younger son and William's brother, is then next in line.
But there are exceptions to these rules, enshrined in the 1689 Bill of Rights and the 1701 Act of Settlement.
The latter was passed to ensure a Protestant line of succession and to exclude a Roman Catholic from ever becoming monarch. It also required the sovereign to swear to uphold the Church of England and the Church of Scotland.
The 2013 Succession to the Crown Act amended these rules so that gender no longer was an issue, ending the male primogeniture system which meant a younger son would become monarch ahead of an elder sister.
It also got rid of the rule barring anyone who married a Catholic from becoming king or queen. However, it did clarify that any of the first six people in line to the throne must have permission of the monarch before they marry.
QUEEN CAMILLA, QUEEN KATE?
The wife of a British king is known as a queen consort, distinguishing the role from that of a reigning female monarch such as Queen Elizabeth II.
As such, queen consort is the official title for Camilla, Charles' wife, but following their coronation in May, she is referred to simply as Queen Camilla.
That tradition means that when Prince William becomes king, his wife Kate, currently the Princess of Wales, will be known as Queen Catherine.
However, the husband of a reigning queen is only known as a prince consort.
WHO ARE TOP 10 IN LINE?
Currently the line of succession is:
1) Prince William, 2) Prince George, 3) Princess Charlotte, 4) Prince Louis, 5) Prince Harry, 6) Prince Archie (Harry's son), 7) Princess Lilibet (Harry's daughter, 8) Prince Andrew (Charles' younger brother), 9) Princess Beatrice (Andrew's eldest daughter), 10) Sienna Mapelli Mozzi (Beatrice's daughter).
(Reporting by Michael Holden; Editing by Angus MacSwan)