Brian Cox finds himself here in the homeland, and he’s not going to lie: “That was a shock.” Dundee’s most famous living son – back in Tayside over 50 years after leaving for London, drama school, Edinburgh Lyceum, Birmingham Rep, the Royal Shakespeare Company, Hollywood, Hannibal Lecter, proper movie star success, a home in New York – has returned to Scotland for a bit of summer work. This bright Sunday morning finds the veteran actor drinking coffee across a vast table in a conference suite at Gleneagles in Perthshire. The five-star hotel is the latest stop in a month-long filming tour of Scotland that has already taken in Glasgow, Ayr and three night-shoots at the V&A Dundee.

Cox’s shock, though, is not that his latest TV project, Succession, HBO’s terrific, BAFTA-winning series about ordinary billionaire media folk, has brought both he and his character back to their shared ancestral roots. It’s that his character – cut-throat patriarch Logan Roy, grouchy boss of all he surveys, including his four sadsack children – is Scottish at all.

“We’d [done] nine episodes on season one…” the 73-year-old starts to tell me, then stops. Rewind. Succession was created by Londoner Jesse Armstrong (Peep Show, Fresh Meat) and co-executive produced by American director Adam Mackay (Anchorman, The Big Short). A punchy dramedy about New York-based entertainment and media conglomerate Waystar Royco, a family firm with global reach, the series is richly characterised and deftly plotted. It’s also thrilling, appalling and laugh-out-loud funny in equal measure.

But if the onscreen fun is twisty, the characters’ backstory is even more so.

“Ages ago, before we started, when they first asked me about the job,” Cox continues of a show that premiered on Sky Atlantic last summer, “I said to Adam Mackay and Jesse Armstrong: ‘Wouldn’t it be interesting if Logan was Scots?’ And Jesse, being an Englishman, said he’s got to be American. But Mackay, the American, thought that would be good. Then it was nixed,” Cox shrugs. In a five-decade career, he’s been-there, done-that enough to know that in TV, as in Hollywood, nobody knows anything.

“So, fair enough. The compromise was, [Logan] was born in Canada, a native of Quebec. But I wasn’t doing a Canadian accent, I was doing a sort of mid-Atlantic mush!” he laughs. “And then finally, on the ninth episode, Peter Friedman, who I’m endlessly sacking,” he smiles of the actor who plays Logan’s Chief Operating Office and confidante, “said to me: ‘I just did an ADR session – a dubbing session – and they’ve changed your birthplace. Yeah, it’s Dundee, Scotland.’

“And I went: ‘That’s my birthplace.’ ‘Oh, that’s a coincidence.’ I said: ‘I don’t think it’s a coincidence!’” he laughs again.

“So I went off to Jesse and asked him: ‘What’s all that about?’ And he said: ‘I thought it’d be a little surprise…’ “‘It’s more than a bloody surprise,’” relates Cox in a gravelly chuckle, “‘I’ve been playing it a certain way and now I’ve got to–’”

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Again, he stops, but the meaning is clear: after filming nine episodes, the actor would have to make an internal calibration. Logan Roy was now a Scottish expat, and the truth of his journey from hardscrabble 1940s Dundee to king-of-the-world in Manhattan would surely reveal itself to be intriguing indeed.

So it came to pass that, in season two, that backstory is explored. Sadly, for now it must remain intriguing. The scenes shot in Scotland this summer comprise episodes seven and eight of the new ten-part season. That’s too far into the run for HBO to allow any plot-spoiling details to be revealed at this pre-broadcast stage.

That said, given Logan’s general irascibility, and his curious relationship with his semi-estranged brother Ewan (played by James Cromwell), it will come as no surprise to Succession fans that the Roys’ Scottish childhood was complex to say the least.

Cox’s return to Dundee, then, has certainly been more straightforwardly pleasing and rewarding than it is for his character. He tells me that in the city of his birth, the V&A is “fantastic” and the redeveloped River Tay waterfront was “unrecognisable” to him.

“The whole of Dundee is incredible,” he beams with a nostalgic twinkle. “It’s amazing what they’ve done to the city. I’ve always thought Dundee was a city of survival. They [call it] the City of Discovery, but Dundee’s been battered so many times. But Dundonians are great, lovely people. But it’s been really beaten up.

“I grew up in the 1960s, when it was one of the most corrupt town councils ever – they were literally demolishing the town. All the Overgate area, which was wonderful, these old stone [buildings], and was medieval…

“Of course, if it was Edinburgh they wouldn’t have touched it. But these crooks,” he says bitterly, “one guy was in the demolition business, so he made a fortune out of it,” Cox notes pointedly. He’s referring to the late Tom Moore, a plant hire businessman who became Lord Provost in the city (actually, that was in 1973), was sentenced to five years on charges of corruption relating to development contracts in the city, but later had his conviction quashed.

Still, to Cox’s co-stars, seeing the show’s on- and offscreen patriarch back on home turf was a treat. Alan Ruck plays Logan’s son from the first of his three marriages. Connor Roy is no businessman, but he does (seriously) think he’d make a great President of the United States. Such is the Roy corporation’s political power, Connor thinks his dad can fix that for him.

“We had a scene in Dundee the other day,” begins Ruck. It involved him, Cox and Hiam Abbas, who plays Logan’s current, third wife, Marcia. “We were driving around and [Logan] said: ‘Ah, the old carousel…’

“I said: ‘What happened there, pa?’ And Scott Ferguson, our producer, said it was so wonderful to watch Brian, as Logan, reminiscing about his boyhood in Dundee – on Brian’s actual birthday!” he laughs of scenes shot on 1st June. “You can’t beat that. You couldn’t write a better scene. And [the emotions] came right out of him. For Logan, it was a very soft and sentimental [side] that you just don’t see from him too much.”

“Brian was so proud to show the city to us, and he told us a lot of stories,” echoes Nick Braun, who plays dimwit cousin Greg, a character who’s a punchbag for Logan’s son-in-law, the toxic clown played by British TV drama stalwart Matthew Macfadyen. “Being here was a great choice for them to take the story. But Brian’s accent’s got so thick since we’ve been in Scotland. We can hardly understand him anymore!”

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Keeping up with Succession can be almost as challenging, but no less rewarding. The first series saw an embattled Waystar Royco dealing with a hostile takeover bid, partly orchestrated by eldest son Kendall (Jeremy Strong). But it’s testament to the skill of Armstrong and his writers’ room that the boardroom machinations and quickfire business jargon never bogged down or obscured the entertainment.

Equally, they know how to craft a humdinger of a plot development. Kendall’s entire secret, Shakesperean plot to kill – in corporate terms at least – his father came to a cataclysmic halt at the end of series one. At the English castle wedding of Logan’s daughter Siobhan (“Shiv) to Macfadyen’s Tom, Kendall’s drug abuse issues caused the death of a young waiter in a traffic accident.

In gripping scenes, Kendall had to drag himself from a car submerged upside down in a pond in the dead of night, and make his way back to the wedding party over rain-sodden fields. When his father learns what happened, he covers up the crime – the price for Kendall being (other than trauma and guilt, obviously) that his father now has him firmly under his heel.

When I ask Strong how it was shooting those scenes, he sounds traumatised still.

“It was… It was…” he starts, stuttering. “I mean, listen, my driver here [in Scotland] drove Chris Pine around for six months doing Outlaw King, and those guys were in the freezing cold and rain and mud, battling for five months – and that film was incredible,” he enthuses of David Mackenzie’s 2018 film about Robert the Bruce.

“But my point being: I found that sequence to be very difficult and harrowing for me. They were extremely difficult nights, and I felt a need to experience as much as I could, what that would have been like, and how harrowing it was for [Kendall].

“So, we’re in a lake, in England, in winter, and those nights I would find myself going through thorn bushes and thickets in the woods, in between takes and set ups, just trying to sustain the stakes.”

Series two starts barely 48 hours after those events. In a sensational performance from Strong, Kendall ghosts through scenes, shellshocked while having to do his father’s brutal corporate bidding to shore up Waystar Royco in a rapidly changing media world. His argy-bargy brother Roman (Kieran Culkin), continues his mission to stab Kendall in the back at any opportunity.

These high-rolling, highly duplicitous individuals aren’t the most pleasant – they’re downright repellent half the time – but you can’t take your eyes off them.

As Macfadyen notes with a grin, “there was a review in the States that described me as a human grease stain. I was really pleased with that.”

Explaining the overall narrative arc of series two, Jesse Armstrong says: “There’s a lot of mergers and takeovers in the media world – as there have been for a long time, but it feels like its accelerating now. And I guess part of that is the threat of Facebook and Amazon and Netflix and Google. Our show is meant to be a reflection of the real world, so that tech-pressure is there in the show.

“We ended last season with a potential takeover bid, so there’s that. And beyond that, there’s a feeling amongst all these so-called legacy media companies: ‘Sh*t, what are we gonna do when our lunch gets eaten by tech firms?’”

The obvious comparison for Logan Roy, his business and his children is Rupert Murdoch. I ask Sarah Snook, who plays Shiv: as an Australian, does she see a lot of Murdoch in Logan? She nods.

“There’s a lot of Lear in Murdoch, a lot of Roman behaviour, Greek behaviour, all mythological behaviours in any of those dynastic families like the Redstones or Murdochs or Packers. Any dynastic family that has wealth and power, it ends up lending itself to these grand, legend-sized stories. So if there are similarities, of course it’s because we’re doing that kind of story. But they’re fun to play!” she says brightly.

Those resonances, she thinks, are why Succession was so successful (instant critical hosannas and positive viewing figures in the US saw it recommissioned by HBO after only one episode had broadcast in America).

“Maybe it’s the right time for it, the zeitgeist, the moment,” she muses. “We’ve got the patriarch of a family who’s in a very powerful position in America at the moment; who’s been well-known as that dynastic power family in New York, famous for years before he became President. So that’s a real switch – it’s not just a politician who’s become President, it’s a personality. And I think that certainly would help people’s interest for this kind of show.”

There’s another added edge to Succession series two: a new character, played by Holly Hunter. Rhea Jarrell is “the politically savvy CEO of a rival media conglomerate”. Was the star of The Piano a fan of series one?

“Oh, so much,” she replies when I meet her in another Gleneagles suite later in the day. Watching the first ten episodes, “I found that I wanted to spend time with these people. It had nothing to do with whether I liked them or not. I just found each of them and the[ir] world utterly fascinating. They’re missing so many things in their lives that you feel empathy for them – even though their acts can be quite despicable.

“There’s a humanity,” she continues, “due to the lack, the subtraction of things they didn’t get when they were growing up. When you meet the mother, and you see the father, you can have empathy for the children. But at the same time,” Hunter smiles, “they’re all quite funny.”

They’re also all, despite their exalted circumstances, real. Jesse Armstrong has taken care to colour the characters’ backstories as deeply as possible. When I ask Jeremy Strong if he noticed a difference in his onscreen dad when they were filming in his hometown, his face actually lights up.

“Yeah, it was quite wonderful, actually. I read Brian’s autobiography, which he wrote about 40 years ago, and he talks a lot about his childhood in Dundee. I’m glad I did read that – I sort of read it because it’s something Kendall would have done,” he cheerfully admits. “But I gained a lot from it. And he brought his sister to set one day, who I think is 89 and raised him essentially, so it was very moving.”

As for what’s next for the Roys, even the clan leader admits he’s blithely in the dark. Partly that’s down to the realities of long-form television: ten hours of programming mean there’s lots of wiggle room for plot development. And partly that’s down to Armstrong’s writing style: endlessly seeking to improve his scripts, he’s not averse to making last-minute, reactive switches, as evidenced by Brian Cox’s account of how Logan Roy came to be a Dundonian.

“When I first started I was a bit annoyed about the fact that I didn’t know what the next episodes were,” admits Cox with another chuckle, “there was no sense of it.

“But now I get a kind of frisson out of the fact that I don’t know what I’m doing. So I find it actually quite exciting that I’m in this no-man’s-land and I just don’t know where this show is gonna go.”

Succession launches at 9pm on 12th August on Sky Atlantic