Just days before his eldest son Prince William marries his university sweetheart Kate Middleton, Charles has overtaken the record set by his great-great grandfather king Edward VII.

The prince became heir apparent when his mother, the then princess Elizabeth, acceded to the throne to become queen on February 6, 1952.

Edward VII was born the heir apparent on November 9, 1841 when his mother, queen Victoria, was already on the throne.

By the time he took over as king when she died on January 22, 1901, he had been heir apparent for 59 years, two months and 13 days -- the milestone that Charles passed on Wednesday.

Charles, 62, was just three years old when he became the heir to the throne.
He could well wait a while yet to become monarch. Queen Elizabeth celebrates her 85th birthday on Thursday, while her mother lived to the age of 101.

The heir apparent, the eldest son of a sovereign, is the next in line to the throne whose right to succeed cannot be altered by the birth of another.

As Charles' eldest son, William, who marries on April 29, is second in line to the throne.
Britain's Deputy Prime Minister Nick Clegg, who is responsible for constitutional reform, said on Saturday he was looking at the possibility of changing the rules of succession.
He said he wanted any daughters born to William and his new bride would not be superseded by their younger brothers.

Changing the laws would require agreement across all 16 realms where the British monarch is the head of state, such as Canada, Australia and Jamaica. Negotiations are under way.