King Charles III succeeded his mother, Queen Elizabeth II, after she passed away “peacefully” on Thursday at Balmoral Castle in Scotland.

The king has been waiting in the wings to claim his birthright since he was toddler, with young Princess Elizabeth ascending to the throne when she was just 25.

What followed is the longest reign in British history, with the 96-year-old celebrating her Platinum Jubilee earlier this year.

The king too marked his own milestone as the longest-waiting heir apparent in British history.

The king, who will be crowned in due course, now takes his place at the head of the monarchy at the age of 73, the oldest of any royal.

And as the king is due to celebrate his birthday on November 14, it’s likely his coronation will take place when he’s 74.

There’s only one U.S. president who was older than Charles when elected commander-in-chief, and that’s the incumbent, President Joe Biden.

According to POTUS.com, Biden was 78 years and 61 days old when he was inaugurated on January 20, 2021.

The next eldest to assume the position of U.S. president follows the chronological order of leaders, with Donald Trump in second place at 70 years and 220 days old.

Charles outstrips his next closest monarch in age by nearly a decade, with King William IV, who ruled from 1765 to 1830, becoming sovereign when he was 64.

Theodore Roosevelt remains the youngest person to assume the U.S. presidency, at 42 in 1901, following the assassination of William McKinley. John F. Kennedy is the youngest person to be elected to the office, age 43 in 1960.

In contrast, the youngest in British monarchy history is King Henry VI, born in 1421, who became king the following year at just 8 months old.

The POTUS website noted: “On average presidents are sworn in at 55 years old.”

Charles has met 10 U.S. presidents, stretching back to Dwight D. Eisenhower in 1959, usually as the world leaders enjoyed an audience with the queen.

Curiously the queen met 13 out of the last 14 presidents, save for Lyndon B. Johnson.

In office from 1963 to 1969, a tweet from the LBJ Presidential Library in 2018 seemingly explained why a meeting never went ahead.

It said: “President Johnson and Queen Elizabeth corresponded from March 1964 to July 1967.

“Nothing serious—congratulations on births, birthday wishes, and a condolence message after the death of [Winston] Churchill.

“Queen Elizabeth never sent an invitation to President Johnson to visit Great Britain. And, President Johnson never sent an invitation to the Queen to visit the United States.”

Also on the list of U.S. leaders Charles has met over the years are Richard Nixon, Jimmy Carter, Ronald Reagan, George H.W. Bush, George W. Bush, Bill Clinton, Barack Obama, Donald Trump and Joe Biden.