Chris Columbus' casting search for 'Harry Potter' as influenced by Macaulay Culkin.

The 66-year-old filmmaker - who directed 'The Philosopher's Stone' and 'Chamber of Secrets' - has reflected on how his experiences working with the child star on 'Home Alone' impacted his outlook on casting Daniel Radcliffe, Emma Watson and Rupert Grint in the big screen adaptation's of JK Rowling's wizarding saga.

Speaking in Demi Lovato's new Hulu documentary 'Child Star', he said: "We went from shooting ‘Home Alone’ [where] nobody cared, but in the course of a year, Macaulay Culkin became a huge star, and that was unexpected.

“It’s not like ‘Harry Potter,’ where you know that it may be extraordinarily successful…

"I came from a working-class family, and I’ve seen it a couple of times with kids when you see someone who comes from a working class family, and suddenly they’re thrown into — the kid becomes the breadwinner for the family.”

He noticed that, from the very beginning, his casting for 'Harry Potter' was capturing the imagination of the whole world.

He added: "You go on the street, you go into a pub, you go anywhere, and people are saying, ‘Who are you gonna cast? Who’s gonna be Harry Potter, who’s gonna be Harry Potter?’

"You take that information and you bring it back to the actor and the actor’s parents: ‘This is gonna get pretty intense.'”

He "felt a tremendous responsibility" to ensure any child cast in 'Harry Potter' "knew what they were getting into", particularly as he'd seen how Culkin - who has since been outspoken about his troubled family life, including his "abusive" father - struggled with fame.

Columbus said: "Suddenly, I realised that parents had to be a big part of it.

“I can’t have [an actor] go home to a really sort of shaky environment for the sake of a film. It’s not worth it. It was as important to cast the parents as it was to cast the kids.”