“IT WAS the loneliest film I’ve ever worked on,” says Bill Skarsgard, 27, who plays Pennywise the clown, in the eagerly awaited big-screen adaptation of It.

LEIGH PAATSCH'S IT REVIEW: The great Stephen King horror clown movie we had to have

Widely regarded as the scariest creature to spring from the imagination of horror master Stephen King, It is based on his 1986 novel about a group of bullied preteens known as The Losers Club, who are terrorised by this evil, immortal being.

It served the plot for Skarsgard to remain isolated from the rest of the cast during the shoot so as not to form any bond with them. “It made sense that I was separated from the kids. They were all hanging out together, becoming friends, and I was by myself trying to wrestle this demonic clown that I was going to portray. It was important the kids didn’t see me in makeup until the first day of shooting.”

Skarsgard describes the first scene he shot as Pennywise. “It was with Jack Grazer (who makes his feature film debut) in a very intense scene where I come out of a fridge and I am really up in his face, drooling and spitting on him. I hadn’t met him yet and he looked at me and just went, ‘Whoa! That’s awesome!’” he recalls, laughing.

“I had to keep the essence in between shooting so I would walk around pacing and laugh maniacally, making noises and screams to be in the right tone for the scene.”

“Then they’d go, ‘Action!’ I’d start mocking him, and then I’d charge him and scream and drool on him. Then he’d start gagging because his character has a gag reflex, and then he got hysterical. And as I am doing it — and I am completely committed — I am also thinking to myself, ‘What the hell are you doing? You are traumatising this kid!’ They go, ‘Cut,’ and I am like, ‘Are you OK, Jack?’ And he goes, ‘Yeah, man, that was great, I love what you are doing with the character.‘ He cracks up.

“And I thought I was traumatising this kid. It was very strange.”

Grazer, 14, remembers it a little differently. “I was genuinely scared. One minute he’s asking if I’m OK, and how’s school going, and the next minute he’s trying to choke me,” he laughs.

“And the way he was moving was weird and unsettling.”

Finn Wolfhard, 14, the most famous of the Losers who also stars in the Netflix hit, Stranger Things, says, “The moment we first saw Pennywise, it was like, ‘What did we get ourselves into?’”

Skarsgard, who most recently appeared in Atomic Blonde, says of his demonic appearance. “It wasn’t until I had gotten the job that I knew what Pennywise would look like. I’d sit in the makeup chair and look at myself in the mirror, and every step of the way you see this character coming alive. I really tried to embody this character and worked hard on it, but I was terrified in doing so.”

Becoming It, looking the part, was an arduous process. “It took six hours the first try, but eventually we got it down to two and a half. I have to tell you, it’s not the most comfortable thing in the world. We shot it in the summer in Toronto, which gets really hot. There’s a lot of physicality and so much intensity in the character, and sweat would just build up underneath my bald cap,” he explains.

“Then things would start loosening up at the end of the day, so not the easiest, most comfortable thing to wear, but I think it paid off when you see what we have on the screen.”

The award-winning novel was the best-selling book in the US in 1986. The evil clown character in the book followed the story of the real-life serial killer, John Wayne Gacy (The Killer Clown) in 1978.

Says Skarsgard, “I did research on clowns and I watched a documentary about Coulrophobia, which means the fear of clowns. It explained where the concept of fear of clowns comes from. Interestingly, it wasn’t a collective fear prior to the novel and it really changed the perspective about clowns. It was really impactful and a testament to Stephen King.”

The Swedish-born actor is the son of renowned actor Stellan Skarsgard and younger brother of Alexander (True Blood). What’s it like growing up Skarsgard?

“It’s a Swedish law that if your last name is Skarsgard, you have to be an actor,” he jokes. “But seriously, it’s a blessing and a curse. Wherever I go in my entire career, I will always be associated with my family. When I was younger, that bothered me. Sweden is a small country and my family is really big.”

“When you’re young, you want to be your own person and you want to be responsible for your own career. You don’t want to be judged by, ‘Oh, do you think he is better-looking or do you think he is worse-looking than his brother? He is definitely skinnier.’”

In that moment I felt compelled to tell him he’s the better-looking Skarsgard. He feigns embarrassment, then laughs, and says, “Tell me more! More!’”

Reflective again, he offers, “Being a Skarsgard overwhelmed me at times, but now that I’m older I hope to establish myself in my own right, not just as someone’s brother or someone’s son.”

As the worldwide premiere is just days away, he says excitedly, “I can’t wait for It to be out. Of course I’m nervous, and like everyone else, the anticipation is killing me.”