Robin Williams was turned down for a key Harry Potter role

In a new interview with the Huffington Post, casting director Janet Hirshenson revealed that the 63-year-old comedian, who died in 2014, called director Chris Columbus about the part of the loveable Hogwarts groundskeeper.

However Columbus rejected him on account of his nationality.

“He really wanted to be in the movie, but it was a British-only edict,” Hirshenson said. “And once [Columbus] said no to Robin, he wasn’t going to say yes to anybody else, that’s for sure. It couldn’t be.”

The American filmmaker had previously directed the Oscar winner in 1999’s Bicentennial Man and 1993’s iconic Mrs Doubtfire, but that wasn’t enough to get him to waive his “Brits-only” rule.

Robbie Coltrane was eventually cast as Hagrid in the Harry Potter films. The 66-year-old actor was reportedly J.K. Rowling’s first choice to play the half-giant character and went on to appear in all eight movie adaptations of her books.

The Jumanji star had previously spoken about his thwarted Harry Potter ambitions, telling the New York Post back in 2001: “There were a couple of parts I would have wanted to play, but there was a ban on [using] American actors ...”

Meanwhile, Eddie Redmayne recently revealed he had auditioned for the role of Tom Riddle in 2002’s Harry Potter And The Chamber of Secrets while at university but didn’t get a call back.

“Over the years, I always hoped I might be cast as a member of the Weasley family — I’m colour blind, but I’ve always been told there’s a tinge of red to my hair — but unfortunately not,” he told Empire, referring to the wizarding family’s trademark red locks.

“A lot of my friends, like Domhnall Gleeson and Rob Pattinson, got their Harry Potter moment, but I never got mine.”

The Oscar winner went on to star in Rowling’s latest instalment, Fantastic Beasts And Where To Find Them, which hit cinemas in November, 2016.