Should all go smoothly these next few weeks, Prince Charles and the British monarchy will reach a new royal milestone.
183 years ago, on June 26th, 1830 -- at the age of 64 years, 10 months, and 5 days -- William IV became king upon the death of his older brother, George IV. (William IV is probably best known for being the uncle and predecessor of Queen Victoria.)
Later this month, on September 20th, 2013, Prince Charles will be 64 years, 10 months, and 6 days old -- making him older than the oldest ascendant to the British throne (including the English and Scottish thrones prior to the Act of Union in 1707).
In order for Charles' milestone fully to matter, however, he'll need to outlive and succeed his mother, Elizabeth II, thus becoming Charles III (or George VII, as some predict) -- as the record for oldest heir-apparent or heir-presumptive never to ascend to the throne will still be held by Sophia, Electress of Hanover, heir-presumptive to Queen Anne.
Sophia died first-in-line to the throne at the age of 83 years, 8 months, and 25 days. Queen Elizabeth II will need to live to be 106 for Prince Charles to reach Sophia's age at the time of the Electress's death.
But, otherwise -- should everything go according to plan -- come September 20th, Prince Charles will be in place to become the oldest ascendant to the British throne in its history.