Jason Isaacs was studying law at Bristol University when he “stumbled drunk” into an audition for a student play. He was asked if he could do a Northern accent, he recalls, and “I knew it was the one thing I could do authentically, because I had been hiding it for years.” He won the part.

Originally from a tight-knit Jewish community in Liverpool, Isaacs’ family had moved to Edgware when he was 11. In Bristol, he found himself “suddenly thrust into this world of people who spoke, dressed and seemed nothing like anyone I had ever met before.”

He’d attended the prestigious Haberdashers’ Aske’s Boys’ School in Elstree, but, he points out, when it was a direct-grant school, while at Bristol, “many of them were upper-class people who were so comfortable with each other, and who had been off to these public schools and boarding schools, and had an accent and a lifestyle that was completely alien to me.”

At his first rehearsal, by contrast, he discovered a space in which class and social differences were erased, and he no longer “needed to be self-conscious about being a lower-middle class Jewish kid from North London. No matter what your background is,” he says. 

“You belong in this room, because what you do in this room is unpick who we are as human beings... It felt like the most interesting and intensive thing I had ever done. I just loved it and I took to it addictively.”

Now 56, and with roles in everything from Hollywood blockbusters like Armageddon and the Harry Potter films, to the popular Netflix series Star Trek: Discovery, The OA and The Dark Crystal: Age of Resistance under his belt, it’s evident that he has lost none of his passion for telling stories.

Even so, almost apologetically, Isaacs confesses that to him, “acting has always seemed, in many ways, to be a particularly trivial and narcissistic thing to do. But every now and again, projects come along which have real value.”

He felt that Hotel Mumbai, the film we’ve met to discuss, was one of these. In fact Isaacs was so passionate about doing first-time director Anthony Maras’ recreation of the terrorist attack on the Taj Mahal Palace hotel in Mumbai in 2008, that when he read the Australian’s co-written screenplay he dropped his plans to take the summer off and walk the Machu Picchu trail with his family.

“I thought, ‘I can’t not do it. This is something that looks like not only is it going to be a brilliant film, just as a piece of cinema, but it puts something positive in the world.’”

At the time, his family was disappointed. But then last year, following a screening, one of his daughters (he has two, with wife Emma Hewitt) told him, “That’s the best film you’ve ever been in, Dad. I’m really glad you didn’t come on holiday.”

The movie is a tough, harrowing watch which doesn’t flinch from showing what terrorism looks and feels like. For Jewish viewers there’s also the knowledge that at the same time, terrorists were conducting a massacre at Mumbai’s Chabad House.

Isaacs’ character, Vasili – “a composite of people” — is a “Russian oligarch, a very wealthy, very selfish, very vulgar, deeply unpleasant man” who, like others in the film and their real-life inspirations, sets self-interest aside, amid the bullets and the bombs.

During the four-day siege, 31 people, half of them staff, were killed, out of around 1500 potential victims. “How did 1470 people survive being alone for that long with terrorists whose job it is to pick them off and kill them?” wonders Isaacs. “This is that story.”

He signed on to do Hotel Mumbai in 2016, the year of the Brexit referendum and Trump’s election. Its message of humanity triumphing over hate felt right, he says, because it “gives the lie to the toxic nonsense being spewed around the world that there’s so much that divides us and we should pull our drawbridges up for our particular tribe.”

When he was a teenager in London, the Far Right was on the march, and Isaacs still has “vivid” memories of “hiding in Chinese restaurants when people were sieg-heiling down Denmark Street.

"I remember being chased by a bunch of National Front guys who’d come to beat us up at Edgware Station, and we had a bit of a skirmish with skinheads who went away and came back with the really heavy duty guys with chains and pick-axe handles.” 

Even at his school, there were “plenty of people who might have been able to do well in exams but were still shaving their heads and wearing DMs up to their knees and looking to beat people up.”

Meanwhile, on an estate near his home, “people were demonstrably aggressive towards us,” says Isaacs, “and I just felt vulnerable and ‘other.’”

University was a revelation. There he mixed in circles where no one knew or cared that he was Jewish. “I realised what a bubble I had lived in, thinking that the entire world was out to get us or that we were targets. 

"It was a big awakening for me leaving home, and all of that stuff that had seemed so all-encompassing and was going to be my life forever, turned out to be none of my future life at all.”

Which isn’t to say he isn’t concerned about where today’s growing divisions and rising xenophobia are taking us, here and elsewhere. He recalls being involved in Holocaust Memorial Day a few years ago, and says that for him the slogan ‘Never Forget’ is not to never forget the black and white footage of corpses, information about concentration camps and Elie Wiesel novels he was “steeped in my whole life”, but “never forget how it starts.

"Never forget the language of the propaganda, how the very first notes are struck. Because it’s not hard to recognise that language and things that people would previously, maybe, have whispered in shame, are now being screamed from the roof tops and pass for perfectly reasonable debate in the public arena.”

Hotel Mumbai is a “plea for tolerance and a plea for understanding”, he says, and recognising that there’s more that unites than divides us. As Jews, Isaacs believes we shouldn’t only be concerned for our own safety, but also “listen out for the other groups who are being attacked”.

“When I was younger, I was probably mostly self-centred about being Jewish,” he admits. “But then when I wasn’t in that community, I carried that feeling with me that it’s your responsibility and if you have any ability at all to speak out for somebody or defend somebody you should, because it could be you tomorrow.”

Hotel Mumbai is a Sky Original Film, in cinemas and on Sky Cinema from September 27