Bertie Carvel is explaining why some viewers might find his performance as the deputy prime minister disappointing. “I can’t out-Nick Clegg Nick Clegg. Nobody can be as perfect as Nick Clegg. He is perfect.” Carvel, wearing a superbly tailored blue suit and the kind of beard that’s become programatically unacceptable in LibDem circles since they kicked off the plastic sandals of political impotence and took up the reins of governmental power, giggles. “Make sure that has the right level of irony when you quote it. He’s perfect. So I don’t want to be doing a performance that’s measured by the accuracy of my impersonation. “
But many viewers of Coalition, Channel 4’s TV election drama, will be judging you precisely on that accuracy. And not just you. They’ll be micro-analysing Mark Dexter’s David Cameron, thinking perhaps he isn’t as Brylcreemed or facially lardy as the genuine article; wondering why Ian Grieve’s Gordon Brown makes the then PM look more hobbled by beer gut than memory serves; and perhaps asking themselves if Mark Gatiss is channelling a more deliciously camp version of Mycroft Holmes in his interpretation of Peter Mandelson.
“Some will think I’ve succeeded and some won’t. But what was important was to be across the arguments and the ideas so I could make imaginative leaps about what Clegg is thinking and feeling.” For Carvel, his performance may not depict the truth of what Clegg is or what he said, but it will capture what feels like – for him at least – the truth. “That’s what you’re doing all the time as an actor, saying this does or doesn’t ring true.” He believes that ring of truth is sufficient to carry audiences along. “The key to acting is just don’t fuck it up. People want to believe in you unless they’re arseholes. There are some people who come in primed with schadenfreude and just want you to fail. But most audiences are there to engage in an act of imagination.”

So whether you impersonate Clegg successfully is less important than it would be if you were, say, Jon Culshaw or Mike Yarwood? “That’s right. Is Picasso’s portrait a failure because it doesn’t, in a photorealist way, resemble its subject? We think not. Why? What is it that the artist is seeing and representing that is as true a representation as the photograph? That’s a big question. Plato said everything in the real world is just a shadow of the truth, that there is a kind of ur table – or ur Clegg – out there in some realm that we can’t access.” Carvel giggles at himself again. If only, I think, Clegg had been in some inaccessible Platonic realm in May 2010: British politics would have been very different.
James Graham’s Coalition is set in that five-day interregnum between the end of 2010’s May election and the formation of Britain’s first peacetime coalition government since the 1930s. It’s about power, seduction, compromise and, while it won’t make anyone of Russell Brand’s temper happier about parliamentary politics, it does take us intriguingly into the back rooms of power as it imagines the secret conversations that took place there.
The result is a thriller no less compelling for the fact that the British electorate is familiar with its dismal outcome. “It’s like House of Cards but without the fiction,” says Carvel, who hopes it will cut through cynicism about parliamentary politics. “Since the latter stages of the Scottish referendum, there’s been a lot of talk about re-engaging. If our film can add to this, that will legitimise any journalistic mistakes – if we’ve made any.”
Cavel steeped himself in Clegg biographies and news reports from the time, but studied particularly closely two of the LibDem leader’s speeches that appear in Coalition: his opening remarks in the TV debate with Cameron and Brown; and his speech on the steps of the LibDem HQ in London after arriving from the election count in Sheffield. “I studied where he breathed, the cadences, the rhythms, the gestures – not so much so I could replicate them, though there was that, but so I could get to what he’s like, what makes him tick.

“The anxiety is ‘What gives you the right to imagine what Clegg might have been thinking at those moments?’ and I think it’s perfectly legitimate for art to do that, for art to hold up a mirror to nature. That mirror does it through the prism of artists’ imaginations.”
Here’s one prismatic perspective through which Carvel refracts Clegg. In Coalition, Carvel’s Clegg often tilts his head forward and looks dolefully upwards at his interlocutor with sheepish eyes before his mouth collapses into a diffident smile. It’s particularly effective in giving a psycho-sexual frisson to the scenes in which Cameron tries to seduce Clegg with the promise of political office, reminding me irresistibly of Hugh Grant trysting with Emma Thompson in Sense and Sensibility, or putting out for Julia Roberts in Notting Hill.
But there’s another point: Clegg is one of British politics most accomplished performers of a likable persona (Brown’s too chippy, Miliband too goofy, Cameron too oleaginous). How does an actor capture some of that fascinating drama of self-presentation? Sensibly Carvel won’t be drawn, saying only: “As an actor playing a real person, you have to liberate yourself from playing the real thing. But certainly one of the things about Clegg mania in 2010 was that he seemed to be himself.”
Did you meet Clegg? “I think it would have been very hard if I had. You don’t want to feel that you’re trying to please – it compromises your ability to see.” Would you like to meet him now? “I’d love to meet him. I shouldn’t think he’d want to meet me.” It must be odd to meet someone who plays you. “Horrible! I don’t envy him having to watch me.”
Carvel says he prepared for Clegg in much the same way as he did for his most celebrated role, Agatha Trunchbull, the vile headmistress from Roald Dahl’s Matilda whom he played in Tim Minchin’s musical adaptation, in the West End and on Broadway. “She’s an awful bully and basically a despicable human being. My view is you should try to understand what it feels like to be that person. The most convincing performance comes from working out how you think they feel about themselves.”

Carvel has become one of our most versatile actors – playing a Jewish murder suspect in the Donmar musical Parade in 2008, and a promiscuous gay man in The Pride at the Royal Court the same year. After Coalition, we will next see Carvel on TV in May as the Victorian magician Jonathan Strange opposite Eddie Marsan in the long-awaited BBC adaptation of Susanna Clarke’s Victorian-set 2004 novel Jonathan Strange and Mr Norrell.
The 37-year-old Londoner won a first in English from Sussex University before going to Rada from which he graduated in 2003. It was an expected career move, given that his manifest destiny was surely to be a journalist. His father, John, worked at the Guardian for 36 years until his retirement in 2009, and his grandfather and great-grandfather were also journalists. “Maybe Coalition is as close to being a political journalist as I could get. I’ve got journalism in the blood.”
He draws an unexpected parallel between the two professions. “The notion of integrity in journalism, which I was brought up with, is fundamental. Telling the truth. What you’re supposed to be doing as an actor is telling the truth and that’s a very inchoate thing. But you know it when you come across it – and that’s when it’s good.”
Did playing Clegg make you more sympathetic to those who practice that other derided profession, politics? “I was on Sky Arts just now and realised how much like a politician you are when on camera. Your agenda is to avoid saying something that, out of context, is going to colour your work in a way you didn’t intend. And, in order not to add that colour, you get bleached of anything.”

Are you more more sympathetic to Clegg now? “Whatever you think about his politics – and I’m pleading the fifth about my political views – I do think the notion that he’s emerged as some kind of traitor or pariah is unfair. He comes across as a person of great personal integrity.”
Really? Didn’t Clegg, by convincing his party to enter into a coalition with the Tories, betray not just his party but those who voted LibDem because of the manifesto commitments it abandoned in office? “But politics is compromise. Coalition is compromise. Nobody gets their way. Clegg’s been very free to admit the long nights of the soul he had trying to work out what the right thing to do was. If you’re the leader, you have to lead. The crisis that involves is terribly moving.”
But it’s where Clegg leads his party that is compelling. “It would be a complete heresy,” former LibDem leader Paddy Ashdown tells Clegg at one point in Coalition as he contemplates doing a deal with the Tories. Yet Clegg eventually manages to convince Ashdown and, thereby the parliamentary party to commit that heresy.
Carvel is going from Clegg the political king maker to king who winds up having his body torn to pieces. He will soon start rehearsing Pentheus the king of Thebes, opposite Ben Wishaw’s Dionysus, for the Almeida’s summer production of Anne Carson’s new translation of Euripides’ The Bakkhai http://www.almeida.co.uk/event/bakkhai.
Will Clegg, if not dismembered by crazed LibDem Dionysiacs, suffer a similarly tragic fate? Carvel is queasy about mapping Greek tragedy on to Clegg’s biography. “Who knows what the denouement of Clegg’s story is going to be? Maybe it will be tragic. Maybe it will be that multi-party politics started on Clegg’s watch – not out of hubris or personal ambition, but because he thought it was the right thing to do. Maybe that’ll be his legacy.”
• Coalition is on Channel 4 on Saturday.
Five actors on how they got under the skin of our political leaders

Andrea Riseborough Margaret Thatcher in The Long Walk to Finchley
If ever you are embarking on playing Margaret Thatcher, do not bring it up at a dinner party. It’s the worst thing you could say – everybody has an opinion of her. The reality is that the myth became much more than the woman. Even though my personal political views are completely opposed to hers, I had to learn to empathise with her. I do think that she was judged more harshly because she had a vagina. Decisions that were brutal might not have been perceived or judged so harshly had she been of the opposite sex.
I played the young Margaret: she is 35 when the programme ends. There was a hop and vibrancy in her step then that, 20 years later after four hours of sleep at night, she just couldn’t muster. Everyone says she was led by her handbag, but in her younger years it was the opposite. Her posture was straight. That vulture shape, where her head pecked forward like a bird’s and her handbag came with her, only arrived later. It was a defence mechanism: she couldn’t understand why people weren’t getting on board with her ideas.

Mark Gatiss Peter Mandelson in Coalition
The voice is what I try to get first. He’s got a long face, and his jaw slightly distends, which gives him this flutey voice. There’s something quite vicarish about him. That documentary – Mandelson: The Real PM? – was full of delights and revelations. In that bizarre valedictory speech, as he retook his seat in Hartlepool when people thought he was going to lose, he says: “I’m a fighter, not a quitter.” So strange.
There’s also a stillness about him, which is why people think of him as a reptile. I watched footage of him leaving office after he’d resigned for about the 19th time. He’s leaving his house carrying two red boxes. He sort of floats down the stairs. I tried to get that in the walk.
The prince of darkness tag is something he tries to live up to. He’s very witty and obviously a great dinner-party guest. But it works for him to be seen as this Machiavellian puppet-master. Apparently, he’s very pleased I’m paying him. Maybe he’s a fan of The League of Gentlemen, or Sherlock.

Stella Gonet Margaret Thatcher in Handbagged
I’m Scottish and most of my family were appalled at the idea of me playing Margaret Thatcher. There is not a lot of love for the woman up there. I was looking more for the Spitting Image qualities, rather than an accurate impersonation. Anyone who is so convinced they are right all the time – that whole “No, no, no” approach – is open to caricature.
The key thing was to sound like her. That elocutioned, manufactured voice was the linchpin of a whole image. As she got older and more powerful, her hair got bigger. “Higher and higher,” she would tell her hairdresser. It gave this kind of Elizabethan feel to her power. Her walk was sprightly and ungainly. Her hands were always clenched to the side with that bloody handbag. People just aren’t like how she was. I found playing her was rather lonely. She had no pastimes. Take away politics and she didn’t have anything else.

Mark Dexter David Cameron in Coalition
The more footage I watched, the the more I realised I quite fancied a go at being PM. I think we get used to taking potshots at politicians, but, in fact, behind the suits and slick soundbites, there are some pretty skilled people. I developed a respect I wasn’t anticipating.
At first, I tried to find the “real Dave”. You assume that there’s something behind the politician, that when Cameron arrives home at night he tears off his human mask and there’s this lizard. But the more I watched, the more impossible it was to find. Maybe that’s just because he’s a canny operator who knows when he’s being filmed. But then I thought: maybe the reason I can’t find the real Dave is because the person he presents to us on TV is pretty much him. In the end, I realised that he was just this straightforward, ordinary guy who, at the last election, found himself in an incredible, unprecedented historic situation he wasn’t fully prepared for.

Ian Grieve Gordon Brown in Coalition
He has three different voices: a public voice, an intimate private voice and a relaxed voice when talking to colleagues in the office. People ask me: “Do you do the thing with the jaw?” They’d be disappointed if I didn’t. He does it as a breathing thing. I did it because his voice is a little lower than mine, so I would need to lower my larynx. The way he folds his arms, the way he walks favouring one side then the other, are useful, but you don’t need to exaggerate when the camera is close to you.
There’s a Shakespearean element to politicians now: the acquisition of power, the coveting of power, the losing of power. My take on Brown is that it’s ultimately a tragedy: you have a good man at the centre who has the best intentions, but the machine got hold of him. He has to take a path he doesn’t like. That said, I hated David Cameron – for the first time in my life, the PM was younger than me.
• Interviews by Jenny Stevens and Ben Beaumont-Thomas