In cinemas this week: Filming It: Chapter Two was almost too scary for James McAvoy

If cinema audiences are half as frightened watching It: Chapter Two as James McAvoy was filming it, we’re in for a scary treat.

Two years ago, Pennywise the clown – terrifyingly played by Bill Skarsgard – scared the pants off us in the first instalment, the studio having decided to split Stephen King’s weighty horror classic into two movies.

Now he’s back, and it sounds as if this second half is even more horrific.

“The shoot was great, great people, amazing director, the cast is incredible but there were days on that set when I thought, ‘This is really disturbing,’” admits McAvoy, a huge fan of King.

“You’re looking at the other actors thinking, ‘This is a great gig and I’m really proud to be here with you all but this is really messed up’. In a good way!

“I rarely get terrified by anything. I read that book as a kid and it didn’t really mess with me but reading it again, as an adult, it gave me nightmares.

“I actually had nightmares about Pennywise in a way that I never did as a child. As an actor, you often put on a backstory you never see on screen and I’ve got these ‘memories’ of my character as a young boy from the first film.

“And what Bill does is incredible. It’s not just the scary make-up and the funny voice or whatever, the commitment he puts into it is incredible.

“He’s amazing. The guy who plays the clown is terrifying. He’s a lovely guy and yet he really freaked me out.

“I never liked clowns as a kid and I remember standing there with the rest of the cast, all these adults.

“We’d all done weird, freaky stuff and we are all looking at each other going, ‘I don’t like being here. I don’t like being an actor today.’

“It was a freaky shoot, lots of freaky stuff going on, slightly sleepless nights sometimes because of the images of what we’d shot that day sticking around in my head.”

It: Chapter Two is set 27 years after the first film, in which the young members of “the Losers’ Club” thought they’d defeated Pennywise.

But now children are disappearing from the town of Derry once more and the Losers – all damaged by what they witnessed – have to conquer their deepest fears once again.

McAvoy plays Bill, the leader of the Losers, whose little brother Georgie was one of the clown’s victims in the first film.

In that, Bill was played by Jaeden Martell and the 40-year-old Glaswegian says: “We chatted and he gave me a letter which was strangely articulate, and it was quite strange to have that coming from the younger incarnation of that character.

“After that it was just trying to rip off his best qualities which seemed to be openness and vulnerability, and getting all of that guilt he carries.”

The younger actors are back for flashback scenes, much like in the original novel, and McAvoy says: “Instead of us just standing around going, ‘Oh, I remember that time,’ we get to show it to the audience.

“That’s great because it would be real sad if we had to say goodbye to that cast that the audience across the world fell in love with.

“And actually, in a weird way, this movie resembles the structure of the book, in that it goes back and forth.”

It: Chapter Two (15) is in cinemas from Friday September 6.