Game of Thrones has claimed many victims in its time and my interview with Joe Dempsie – the 30-year-old actor who may yet play a pivotal role in the show’s looming endgame – was very nearly one of them. As filming for the eighth and final series is currently underway, it was unclear whether Dempsie would be given leave from the Belfast set for our meeting in London. Ultimately, the schedule on HBO’s fantasy behemoth shifted, Dempsie suddenly flew home and, with a few hours’ notice, a raven (well, email) was sent, summoning me to the West End.

“Being on Thrones is a bit like when Alex Ferguson was at Manchester United,” jokes Dempsie, buzzcut and casually dressed, when we sit down in a curtained meeting room at Bafta. “There’s that feeling that no one is bigger than the club.” This genial calmness in the face of professional toing and froing is very much in step with the grown-up new project that Dempsie – the Nottingham-raised veteran of Skins, Southcliffe and This Is England ’86 – is primarily here to talk about.

Deep State, which kicks off this Thursday on Fox, is a new, eight-part spy thriller tracking Max Easton (Mark Strong): a former MI6 agent coaxed back for a mysterious mission in Beirut. Dempsie plays Easton’s estranged son Harry, a fellow spy who’s soon swept up in a world of double-crossing, violence and Homeland-worthy geopolitical intrigue.

“The thing that Matthew Parkhill [Deep State’s creator] wanted to portray, that he felt hadn’t been shown in espionage thrillers before, was the human cost of the work these people do,” explains Dempsie. “For me, this show is what I hoped The Night Manager would be because I was expecting something a little bit more cerebral [from that show]. And while Deep State has action, pyrotechnics and spies being spies, it’s not popcorn viewing.”

The actual business of making the series sounds, in some senses, just as challenging. The bulk of scenes were shot on location in Casablanca, right in the thick of indifferent Moroccan crowds. “It’s this lively, bustling, filthy, working port city,” he says. “And the reality is, they don’t give a shit about your scene that you’ve got to film if they’ve got to get from A to B. And in a way it was great, because our characters were trying to blend in. So it was almost like an exercise in authenticity.”

Hopes are high for a second series with an expanded canvas. “There are so many possibilities in terms of other parts of the world,” he says. “And it’s amazing that we’re talking about this in a week when the situation with Russia has escalated diplomatically. It’s a timely, timely series.”

Of course, before any return for Deep State, there’s the small matter of Game of Thrones’ grand finale: six feature-length episodes due on screens in 2019. Dempsie’s character in the show – Gendry, hammer-wielding blacksmith and bastard son of King Robert Baratheon – was last seen sprinting through snow (“The most exercise I’d had in ages,” he laughs) towards a section of the Wall later destroyed by a zombified ice dragon. Was it always confirmed that, having been brought back after three series off screen, he’d be there for the saga’s climax?

“I assumed I was,” he says, with a smile. “But also, there was a scene towards the end of season seven, when Jon and Daenerys are travelling back on the ship. He’s sort of unconscious, someone passes him a bowl of soup and that person was me. The scene got cut but in my mind I was on the boat back. Maybe they were keeping their options open in case they had to do away with me but, I think, in my heart of hearts all I ever really wanted was to be around for the endgame. Just to be there when the reckoning happens.”

Dempsie admits there was a “subdued, bittersweet atmosphere” to the first collective script read but, with filming at around the midway point, he says “brutal” night shoots have helped to keep sentimentality at bay.

“At this point, when it comes to an end, everyone will be fucking relieved rather than sad,” he chuckles. Dempsie also acknowledges that the compressing of the narrative has, as per the critics of the most recent series, led to some muddled plotting (“In terms of the timeline, let’s just forget it”) but hints that the monumental scenes to come will ultimately be worth any bumps along the way.

“At various points we’ve been stood there on these amazing sets, turned to each other and gone, ‘TV history man’,” he says. “And you know, it’s not hyperbole.”

Game of Thrones S7 episode 3 - in pictures 7 show all Game of Thrones S7 episode 3 - in pictures 1/7 Emilia Clarke as Daenerys Home Box Office 2/7 Liam Cunningham as Davos, Kit Harington as Jon Snow Â©2017 Home Box Office, Inc. All 3/7 Peter Dinklage as Tyrion Lannister Â©2017 Home Box Office, Inc. All 4/7 Aidan Gillen as Littlefinger, Sophie Turner as Sansa Stark Â©2017 Home Box Office, Inc. All 5/7 Emilia Clarke as Daenerys, Conleth Hill as Varys Home Box Office 6/7 Conleth Hill as Varys, Carice Van Houten as Melisandre Â©2017 Home Box Office, Inc. All 7/7 Liam Cunningham as Davos, Kit Harington as Jon Snow Â©2017 Home Box Office, Inc. All 1/7 Emilia Clarke as Daenerys Home Box Office 2/7 Liam Cunningham as Davos, Kit Harington as Jon Snow Â©2017 Home Box Office, Inc. All 3/7 Peter Dinklage as Tyrion Lannister Â©2017 Home Box Office, Inc. All 4/7 Aidan Gillen as Littlefinger, Sophie Turner as Sansa Stark Â©2017 Home Box Office, Inc. All 5/7 Emilia Clarke as Daenerys, Conleth Hill as Varys Home Box Office 6/7 Conleth Hill as Varys, Carice Van Houten as Melisandre Â©2017 Home Box Office, Inc. All 7/7 Liam Cunningham as Davos, Kit Harington as Jon Snow Â©2017 Home Box Office, Inc. All

Gendry’s royal blood – and the 11th hour nature of his return to the fray – has led many on the internet to theorise that he could even be the character who ends up on The Iron Throne. Dempsie maintains his poker face but notes that “the longer a loose-end goes untied, the more conspicuous it is”. Whatever his Game of Thrones fate, Dempsie is, after a busy couple of years, looking forward to spending more time in his West Norwood home. And – as someone who is still close friends with Skins graduates Nicholas Hoult, Dev Patel and Daniel Kaluuya – he’s also contemplating the kind of work he ultimately wants to do.

“Increasingly, if you’re a young actor who’s given a great performance in an independent film that’s done well, your reward is a role in a superhero franchise where you stand in front of a green screen wearing a silly outfit,” he says.

“It doesn’t sound like my idea of fun but that’s where the industry is now. Yeah, there have been times when I've gone, ‘I want to do big movies like my mate in the WhatsApp group’. And it’s hard when your friend getting nominated for an Oscar almost becomes an annual event. But I’ve been incredibly fortunate to do the varied work I have over the last 10 years.”

He pauses, reflecting on the distance he has travelled in the decade since he crashed onto screens as a teenage party animal. “A healthy sense of perspective in both directions is important.”

Deep State starts on Thursday 5 April at 9pm on Fox