Prince Charles has become the oldest male heir in British history after reaching the age of 64 years, 10 months and four days.
It means that he eclipsed William IV by one day, who acceded to the throne in June 1830 when he was 64 years, 10 months and three days old, the Daily Express reported.
Only one other immediate heir to the throne has been older, Sophia of Hanover, but she died aged 83 in 1714 before she could become Queen.
Charles, who will be 65 on November 14, may still have some time yet before inheriting the throne.
Royal aides made clear last week that his 87-year-old mother, the Queen, and father Prince Philip, 92, have no plans to step down from public duties.