When the king (male or female) dies, the Crown Prince automatically from that moment on becomes king.
George V
The house of Hanover in 1714, when George I came to the throne.
Prince William
For them he was considered a usurper of the Bourbon throne.
George V was on the throne at the first Commonwealth Games in 1930.
Prince William
Such a person might be called an "agent" or an "aide" (in the USA) or a "locum" (in Great Britain).
Prince William - married Kate Middleton.
He was trying to obtain the throne of Great Britain for himself.
George V was the British monarch on the throne when the inaugural British Empire Games were held in 1930.
In regard to the British throne, it was George III that occupied it in 1816. He was the King of Great Britain from October 25, 1760 until his death on January 29, 1820.
There is no "English Throne." The title "King (or Queen) of England" has not existed since 1707. England is a part of, but the same as, The United Kingdom of Great Britain and Northern Ireland. The person who is tenth in line to the throne of The United Kingdom of Great Britain and Northern Ireland is Her Royal Highness The Princess Anne. See the related question links below.