Traditionally, journalists and actors are supposed to spend the first half, at least, of their allotted time together in some airless hotel room politely discussing The Work – by which I mean the star’s latest project, whether magnificent or corny. But tradition can go hang. Thanks to Harvey Weinstein and all that has followed in the months since his disgrace, such encounters have a strange new energy, a directness that makes short shrift of such matters as awards season and the ordeal of the red carpet. Journalists want to know if the atmosphere in meetings and on set has changed and, if so, whether such a shift is likely to be permanent; their interviewees accept that, for whatever reason, such questions cannot be ducked. For the time being, then, a certain amount of soul-searching is the order of the day.

But perhaps Jason Isaacs would always have been desperate to talk about something other than Monster Family, an animated movie in which he hammily voices Dracula. For one thing, he still hasn’t seen it. For another, far too much of his head space is currently occupied by Donald Trump, a man for whom his fear and loathing seemingly know no bounds. “I’m not a breakfast television presenter,” he says. “I find it hard to go from ‘this fucking monster’ to ‘by the way, my new film opens next week’.” Most of all, though, there is the fact that Jeffrey Tambor, with whom he starred in Armando Iannucci’s satire, The Death of Stalin, is among the ever-growing list of men who now stand accused of sexual misconduct (Tambor, who has denied any wrongdoing, left the award-winning TV series Transparent last November, following allegations of inappropriate language and physical contact). “I found Jeffrey to be so incredibly charming and delightful,” he says. Does he believe that Tambor’s career is now over? “Who knows? America loves nothing more than a second act.”

Isaacs, who has already reminded me that he read law at university, believes that the ongoing situation is complicated; he would, you gather, rather run the risk of being quoted out of context than give in to easy platitudes. “I feel deeply uncomfortable that people are being convicted by accusation,” he says. “It’s open to abuse. Trial by Tweet seems extremely dodgy to me. Plus, there’s a difference between rape and inappropriate comments; between kissing and sticking a hand up a skirt. These are not subtle differences for me. They’re binary. I don’t know what Jeffrey’s story is. I just hope that the truth will emerge, and that he will be judged by that. I want to listen to his accusers, but that doesn’t mean that I’m not crushed by this happening to him, because I am. His work is so brilliant. Can anyone ever truly clear their name after the mud is slung? I don’t think they can. Luckily, I live a spectacularly dull, suburban, bourgeois life. No one can accuse me of anything other than bad puns.”

Facebook Twitter Pinterest Taking the reins: Isaac’s character Dracula, in the animation Monster Family.

Isaacs has just wrapped a series of CBS’s Star Trek: Discovery (he plays Captain Gabriel Lorca); soon, he’ll return to the US to film more episodes of The OA for Netflix. So has the atmosphere changed? He’d surely know if this was the case. “Well, here’s the thing most people don’t realise,” he says: “Whenever you work for a studio, you do a half-day seminar on sexual harassment. Things are laid out very clearly and in a very extreme way. I’ve done so many of them. We’ve all sat through them so many times they’ve become places where you snigger and pass notes to each other. So, the HR rules have been in place for a long time; they certainly don’t need to be amended. It’s more a question of whether the mechanism is enforced. Who would, say, a vulnerable young woman who doesn’t yet have a job report to?”

He thinks #MeToo has empowered young women, and that this can only be a good thing. But now men need to change, too. “How do we confront those who contravene the rules?” he asks, possibly thinking aloud. “Like everyone, I’ve been asked: ‘Why have you kept quiet?’ The answer is: because there are defamation laws. You can’t just say: ‘I’ve heard this person is a pig.’ I’ve heard terrible things, but I would be bankrupt if I’d repeated them. There’s one particular man I hope gets caught. Everyone in the industry hopes he’s going to jail very soon. If I have ever witnessed it [harassment], I have challenged it. I have young daughters, and I’m horrified that everywhere I turn, sex is commodified and women are judged by how they look and how much flesh is showing. I’m mortified by it. I feel like King Canute, trying to protect them from it. But I just don’t know how one legislates. The entertainment business is trying its best. Maybe it’s as basic as saying that people mustn’t have meetings in private any more.”

The things Trump says encourages the worst in people

It’s no coincidence, he insists, that these allegations have come to light at a time when America has for a president a man who “seems to be a poster boy for predation” – and it’s this non-coincidence that, in his darker moments, keeps him going. “The things Trump says and does encourage the worst instincts in people, but they also provoke change.” Nevertheless, it still seems “ludicrous” and even “a little surreal” to him that so many voters decided to throw their weight behind “such a dangerously unstable and ignorant sham of a man… I still find it bewildering: not that people felt betrayed by the political class, but that this was the man they thought would be able to help them.”

Is this why he’s so active on Twitter? “I’m not sure what you mean by active,” he says. “I’m only playing with my mobile phone. I’m not leading marches down Whitehall.”

So he doesn’t occasionally get into fights? A weak smile. “I do it because I’m furious. I want to punch the walls. Occasionally, I can’t stop myself. I can’t stand by and listen to that kind of bile. I’m not a saint. I look at their timelines and they’re full of white supremacists and alt-right Breitbart types.” What effect has all this had on how he’s sees the world? Perhaps it would be better not to look. He shakes his head. “I don’t think everyone’s nasty. And I think there have always been [bad] people in the shadows. But… I am fucking terrified. Beyond all the domestic issues, the trade and the tax, and even beyond his cataclysmic attitude to climate change, that the man they support should have his finger on the nuclear button… We’re seven minutes away from the destruction of the planet.”

Facebook Twitter Pinterest History making: in the Death of Stalin. Photograph: Nicola Dove/EOne

What about art? (I have to admit that I’m slightly amazed to find myself having to nudge an actor in the direction of their work.) Doesn’t it matter now more than ever? “Yes, art can, in difficult times, be cathartic. People still tell me how the characters in Angels in America spoke to them [Isaacs appeared in the first British production of Tony Kushner’s Aids-era play at the National Theatre in 1992]. But if it doesn’t effect change, it’s just a bunch of people wanking in a dark room.”

Isaacs is both famous and not-quite-famous-enough. Fans of Harry Potter, for instance, know him as Lucius Malfoy, and today a PR sits vigilantly in a corner of the room (we’re in a cushion-stuffed hotel just off Oxford Street). But by his telling, he can also travel home from a red carpet event by tube and hardly draw so much as a second glance. “I am busy,” he says. “But I’m often not busy, and like everyone I know in this business, I always think: that’s it. The funnel is narrowing. There’s more work for 35-year-olds [he is 54]. That’s why, when I talk at drama schools, I always tell the students to consider taking the reins from day one. Make stuff, I say. There are deeper satisfactions to be had when you’re not placing your id on the line by waiting for someone else to endorse you.”

What about his id, though? (And, for that matter, his ego.) In interviews, Isaacs always makes such a point of his abject humility, his blessedness, his determination to be a good father (he has two daughters with his partner, Emma Hewitt). Is this for real, or is it just another disguise?

He insists it’s the former. “I’m just a dude who forgets to take out the rubbish,” he says. “I’ve had a good year or two, but there have been other times… I’ve been to Sundance with eight films, and only one of them came out.” Life – or the movies – has taught him to keep things in perspective. “When I was in Peter Pan [he played Mr Darling and Captain Hook in PJ Hogan’s 2003 film], it was going to be gigantic. I was told it would change my life. Be careful, they said; make sure you’ve got the right people in place. Then it came out, and it was a catastrophic flop. It killed my film career stone dead for a while. It was a great lesson. Just have a great time and do the best you can. Sometimes I wish I was more famous; you have more choices as an actor when you are. But I tend to ask: how can I be grateful for the things I’ve got, rather than for the things I haven’t got? Moaning is a waste of life.”

Facebook Twitter Pinterest ‘People still tell me how the characters spoke to them’: with Daniel Craig in Angels In America. Photograph: John Haynes/Lebrecht Music & Art

He was born in Liverpool, the third of four sons in a tight-knit Jewish family; his father was a jeweller, like his father before him. When Isaacs was 11, they moved to the corner of northwest London where he still lives. He attended Haberdashers’ Aske’s Boys’ School in Elstree – “I thought it was going to be like Tom Brown’s School Days, but it was a direct-grant school then, and still very mixed” – after which he went to Bristol University. “I was good at adapting. I’m quite chameleon-like, but everyone sounded like Hugh Grant and Liz Hurley; they had this ease with each other that I couldn’t even pretend to have.” One day, a bit drunk, he stumbled into an audition, where he was asked if he could do a northern accent. “And I could – that and skateboarding were my only skills – and I found that in the rehearsal room, I didn’t feel so self-conscious about where I was from. The discussions were so intimate and so elemental. It sounds pretentious, but it was all about what makes people love and hate, and I became addicted to it.” After Bristol, then, he went to drama school.

Was he ambitious? “No, I drifted into acting, and it has gone well, and I like it. I don’t know if I’d have stuck at it if it hadn’t gone well.” It thrills him that he can still surprise audiences. “When I was sent the script for The Death of Stalin, my honest thought was: this is a mistake. I’m not known for being funny. That’s why I said yes immediately – that and the fact that I’ve been a fan of Armando Iannucci since university.” It was his idea to play General Zhukov with a Yorkshire accent (Brian Glover was his inspiration). Did it feel risky? Not everyone is willing to see the funny side of torture and mass murder. “Yes. I knew it could be an extraordinary misfire in terms of taste, but then I looked at the cast list, and I thought: I don’t care if it goes down in flames. Only when I saw it with an audience did I know it had worked. Fuck me, I thought. It’s brilliant!”

What will we see him in next? He isn’t quite sure. Look Away, a thriller directed by Assaf Bernstein, should come out this year (it co-stars Mira Sorvino, one of Weinstein’s alleged victims). But the release date of The Palace, a film about the 2008 attacks at the Taj Mahal Palace Hotel in Mumbai starring Dev Patel and Armie Hammer, remains unknown. “It was with the Weinstein Company,” he says. And so we end up – somehow, it seems inevitable – right back where we began.

Monster Family is in cinemas and on Sky Cinema now. The Death of Stalin is out on digital, DVD & Blu-ray now