Harry Potter star Jason Isaacs has opened up on what it was like filming a sex scene for his brand new TV drama… but the reason why it was so awkward might surprise you.

The Lucius Malfoy actor portrays Cary Grant in ITV’s Archie, which takes its title after one of the legendary Hollywood star’s birth name, Archibald Leach.

Exploring the late actor’s life from his childhood in Bristol all the way up to finding stardom, he appears in the four-part show alongside fellow cast-members including Harriet Walter, Kara Tointon and Laura Aikman.

Laura – who’s depicting Cary’s ex-wife Dyan Cannon in the drama – joined Jason for an interview on the latest episode of Channel 4’s Sunday Brunch.

At one point during their chat with presenters Simon Rimmer and Tim Lovejoy, Jason, 60, Jason explained that the majority of Archie was filmed ‘in a converted factory in Liverpool next to an open sewage’, with some scenes also shot in Spain.

After Simon and Tim exclaimed with shock at this revelation about the UK location, shattering the illusion of an old-school Hollywood backdrop, the Star Trek actor offered another interesting tidbit.

Jason revealed he and his co-star were ‘trying not to gag on each other’ (Picture: Channel 4)

The actor certainly mastered Cary Grant’s signature suave demeanour (Picture: Matt Squire/ITV)

‘I remember someone asking me – we’ve been doing a bit of publicity recently – is it awkward shooting sex scenes. There’s a little bit of that going on,’ he shared.

‘And I said what was awkward was the smell of the sewage from next door, trying not to gag on each other.’

Earlier this year, fans of Jason were offered a first look at his transformation into Cary Grant, as he embodied the icon’s debonair swagger in first look images.

Cary died in 1986 at the age of 82, after he suffered a stroke.

Cary Grant is still remembered as one of the most iconic actors of his era (Picture: Silver Screen Collection/Getty Images)

In his life, he gained renown for both his dramatic and comedic roles, appearing in films including An Affair To Remember, His Girl Friday, The Philadelphia Story and Bringing Up Baby.

Cary was married five times, and had one child with his fourth wife, Dyan. Their daughter, Jennifer Grant, was born in 1966. Both Dyan and Jennifer are executive producers on Archie.

In an interview about the drama telling the story of her late father, Jennifer told The Times: ‘My gut feeling is he’s pleased about it. Sometimes things take generations to heal. I wanted to show dad’s humanity and that included his imperfections. You didn’t have to walk on water to be Cary Grant.’

Sunday Brunch airs on Sundays from 9.30am on Channel 4. Archie is available to watch on ITVX.

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The actor revealed he and his co-star were ‘trying not to gag on each other’.