Walking out of a small, dark screening room after the credits started rolling on Maxine Peake's latest film, Gwen, I felt a little broken. Rather than jumping on the tube as I might normally, I walked home. The idea of being in close proximity to normal life – to people being happy – just felt too much, almost disrespectful.

Set in 19th century Snowdonia, Gwen – written and directed by William McGregor – tells the story of a family crushed by the evils of capitalism; of working class women being fucked over by men. It's very much Maxine Peake's territory. She plays Elen, the mother of two young women with an absent father. Over the course of 84 minutes, their lives are destroyed by the violence, ambition and unfettered greed North Wales' rich and powerful.

Much like Mike Leigh's Peterloo – the last feature I'd seen Peake in – Gwen is a film that feels purposefully slow and painful. I don't think it's a spoiler to tell you it doesn't end well; an uplifting and hopeful summer blockbuster it is not. At a time in which the world feels increasingly hopeless and politically volatile, I'm left asking myself two questions: why does Peake want to tell these stories of oppression and injustice? And with so many awful things happening at the moment, why now?

"I mean, obviously, what you want is the audience to be moved by it," Peake tells me. "But, for me, the main thing to take away from the film is how it parallels politics in the modern day. These are still the struggles that we're having. I want people to compare the story to those taking place today."

We're sitting in a small room in an upmarket private members' club in Covent Garden. Following a quick photo shoot – before which she reapplies her trademark bright red lipstick – the PRs, photographers, assistants and groomers file out, and we're left alone. Within seconds, Peake is telling me about the industrial revolution and the evils of neoliberalism; about the need for a radical upheaval in the way we live and work. These are not topics I tend to cover when interviewing famous people; for Peake, it's nothing out of the norm.

Born in Greater Manchester in the mid-1970s, politics has long been a presence in the actor's life and work. The backdrop to her formative years was striking miners, the Cold War and Thatcher. Back then, she says, it all felt much simpler: "It was the baddies against the goodies. It all feels much more fractured now."

"My dad's the opposite end of the scale to me," says Peake when I ask where her views come from. "The worst breed: a working class Tory. He's very proud, and describes himself as a capitalist without any capital. I don't know why, though," she says, laughing. "He's never had a pot to piss in."

It was, in fact, her step-grandad Jim who introduced her to the ideas of the progressive left. A long-standing member of the Communist Party, as a teenager Peake's evenings were spent listening to him speak, getting to know the visitors from Russia, Ireland and beyond who'd come to stay at the house for meetings.

"It breaks my heart when everyone thinks people past 60 are all some sort of white supremacist," she says. "Until he died, he was fascinated by the generations coming up and what they needed and what we needed to provide for them. He had a huge influence on me."

That said, Peake ignored the one piece of advice he impressed on her most often: to stay away from the struggle. "He said, 'I don't want you to get involved,' that it would take over my life," she explains. "He said he'd be upset if I spoke about politics – he thought it would damage my career. But you can't help but talk about it. I'd have been lying if I didn't." And so she did. It’s why the 44-year-old is as known for her roles in Dinnerladies, Silk and Shameless as she is for her views on climate change, Labour and women's rights.

Twenty minutes in, I offer to bring the conversation back to the film, to be polite – because so far we've talked about the automation of the workforce, the politics of Shameless and how hard it is for young working class actors to get a break. But Peake makes it clear that won't be necessary. Instead, we turn to Jeremy Corbyn.

"I am a Corbyn supporter," Peake told the Guardian a couple of months before the general election of 2017. "My mind boggles why people treat him like the anti-Christ, but it goes to show people are a lot more right-wing than they like to believe." Labour went on to surpass expectations, but at the time – just like now – there were some within the party who'd given up.

"Well, it's hard, isn't it. But there's a point where you have to think to yourself that you've nailed your flag to the mast," she says. "What we do now is see a little sign of a blip, and everyone panics and moves away. You have to remind yourself: it's not called the struggle for nothing."

Peake was "really shocked" at people who had previously been supporters jumping ship before the last election. "Come on, guys," she says, "that's not how it works. Have faith. I joined the Labour Party not because of Jeremy Corbyn, but what he stands for. Oh my god, a Labour Party that might actually be Labour, be socialist. We hadn't seen it in my lifetime. Of course there are complications, the wheels might look like they're falling off. But if we don't stick behind it then what have we got?"

After years of rejections from drama schools, Peake moved to London aged 21 after finally being offered a place at RADA. "I never envisaged that my class would be at the forefront of what I did," she explains. "I started to realise when auditioning for jobs that it was. Of course I thought, 'It's obvious to you that I'm working class because of the way that I talk.' It became an issue."

Twelve years later she returned to live in Manchester, a move she says impacted both her ability to be more selective in the work she takes, and her political outlook. "Being up north, you do get a very different view of it," she says of Brexit. "The EU isn't some sort of progressive saviour – it's a lobbyist, neoliberal institution. Suddenly it feels like the London elite are not getting their own way and don't like it: 'Ooh, all those racist northerners,' they say, rather than listen to what so many are actually saying and why."

As far as Peake sees it, many of the most vocal and ardent remainers come from a place of privilege, middle class types from the south who can afford to make Europe their only concern.

"I want to shake people and explain it was shit for lots of people before Brexit; this country is going to be shit for lots of people after," she says. "There comes a point where it feels like a smokescreen is blinding everyone, a distraction. People saying they won't vote Corbyn now because of Brexit, and they'll vote Lib Dem instead? It's just not the only issue. We need to get the Tories out. Even when I wasn't a member of the Labour Party I still voted Labour. I couldn't bear Tony Blair, but I still voted Labour. That's what you did, even if some of the policies or ideas weren't exactly what you believed in."

I don't make a habit of asking everyone I interview to lay out where the stand on the treatment of trans people, but our chat is during Pride month, Peake is an outspoken and vocal feminist and she played a trans Hamlet at the Royal Exchange, Manchester, in 2014. She also seems keen to talk with me about big, important issues, and – as we await the results of the government's Gender Recognition Act consultation – this is a topic worthy of that characterisation.

A small but vocal group of feminists – many of whom are of Peake's generation – seem to be making it their life's mission to attack trans men and women, doing all they can to halt progress and the advancement of trans rights. So I ask how she sees it. For a moment, for the first time, Peake hesitates. I get the impression she knows where she stands, but maybe hasn't discussed the topic in an interview before and wants to make sure she gets it right.

"I mean, it's not that I can see both sides, but it's interesting that I can see… you know what I mean?" she says, momentarily stuttering. "And yet, if you're trans then you're a woman. Do you know what I mean? I've had friends who say they feel unsafe in spaces, but… what do I say? What do I say?"

She takes a moment.

The reason I'm asking, I tell her, is that it feels – all too often – that a vocal minority of transphobic feminists claim to speak on behalf of all women, and I’m wondering if she'll take this opportunity – as she so often does – to give a marginalised community her support.

"It's about trust and respect," she replies, on firmer ground. "We’ve got to embrace and trust people in all sections of society. If people break that trust, then of course you deal with it – if it's a specific person in a specific place. But I do think it's an important issue. We need to take in the whole trans community. It's about inclusivity. What's your view?"

Peake in 'Shameless'. Photo: Company Pictures / Channel 4

I talk about the parallels between the awful treatment of trans people now and lesbian and gay people through the late 20th century; about the unpleasant alliance being forged between TERFS and the far-right.

"I suppose there is always going to be that section," Peake offers, "but a woman is a woman is a woman. If you identify in that way, then you're a woman, and that’s that."

With that, there's a knock on the door. Our time together is almost up. I think back to my walk home from the cinema, at despairing at the world around me, all the injustices. I ask my final question: despite all we've talked about, does she still live in hope?

"Always," she replies, grinning, "else I'd throw myself in the air without a parachute." While not in a constant state of positivity, she clarifies, she keeps her faith: "There are days when I really despair at humanity, but I do feel hopeful. You just never know. Even though, on paper, the world seems pretty awful, there's always hope of change. It's how we survive as a human race."