sentences:  The oldest male heir presumptive was Ernest Augustus, King of Hanover and Duke of Cumberland, who was displaced as Queen Victoria’s heir by the birth of his great-niece Victoria, Princess Royal, when he was aged .The oldest monarch at the start of his reign was William IV who succeeded to the throne in 1830 at the age of 64 years 309 days.If the current Prince of Wales became the King today, he would be the oldest to do so at the age of .