Alan Cumming: 'I'm a fabulous, top, international actor'

In the top-floor bedroom of a 300-year-old house in London's East End, Alan Cumming is holding court. Clad, a little informally, in a stripey matelot T-shirt that has seen better days and a pair of grey, fleecy jodhpurs, the Scottish actor is telling a small throng of associates about the house's unusual history. It's called Dennis Severs' House after the Californian-born artist who lovingly refurbished its 10 rooms with the furniture, pictures, clothing, knick-knacks, teacups, candles, flowers and even food of the 18th and 19th centuries.

Mr Cumming loves a bit of tat. As he stands amid the paraphernalia of Georgian-era lunch – pewter tankards, wine goblets, wigs, polished oak – his eyes gleam as if he's on a movie set. He dismisses my suggestion that this house is basically three storeys of Antiques Roadshow, but his attention is distracted by a Victorian pamphlet warning against sodomy and he dashes to inspect it. Unfortunately the text is in Latin.

What's he doing here? He's presenting a series of documentaries called Urban Secrets, in which he visits eight cities – London, Bristol, Brighton, Liverpool, Newcastle, Dublin, Edinburgh and Glasgow – and goes about discovering secret nooks and hideaways, and talking to the locals.

Mr Cumming lives in New York City, where everyone knows him from the Emmy-winning TV show The Good Wife. What would make him want to visit Brighton, to investigate its sewers? "I've done lots of documentaries over the years," he says defensively. "I did one for the BBC about the real Cabaret, when I went to Berlin and researched what happened to the real artistes. I did one about Scottish films, another about Scottish humour. With Urban Secrets, I just really liked the idea of wandering around chatting to people."

Chatting? It's very funny to watch the camp, mischievous Cumming as he bamboozles the chap in charge of the unwanted-pulpits room at St Paul's, or raises an arch eyebrow as the guy in the London Silver Vaults explains the function of a 'beef trolley', or listens with distaste to the sewage historian explaining how Victorians enjoyed communal bowel evacuations and wiped themselves with sponges on sticks.

But dear God, one doesn't envy the continuity people. For Mr Cumming is very easily distracted. I try to interview him while walking through the backstreets of Spitalfields and Shoreditch on an 'alternative London' tour. It is like walking a dog – specifically a Jack Russell, what with Mr Cumming's sharp nose, pointy ears and eager demeanour. Every time the conversation threatens to pursue a straight line, he spots something that takes his fancy, and dashes off. Sometimes it is the street art, sometimes a memory of once filming a scene at that very intersection. Once, as we discuss the Bristol Hippodrome, his voice drifts off while he cruises a poster of Justin Bieber.

"I'm quite good, though I say it myself, at making strangers feel at ease," he confides as we pass The Ten Bells pub, where many of Jack the Ripper's victims drank their last. "They tell me things more than they might normally to another person. I think I have an openness that I exude..."

He collects eccentrics as others collect tattoos. "You meet these crazy people who don't need me to bring them out of their shells. Under Brighton station, there's this toy museum, like a little boy's dream. You have to crawl underneath it and stand in the middle of the trains. The owner does station announcements..." He extemporises, covering his mouth with his hand and pronouncing a muffled "ThetrainnowarrivingsthethreefortysixfromChesterstoppingatCrewe... He was as mad as cheese. And I met a lady who sings songs while wearing a hat that rotates and produces sounds in conjunction with the lyrics."

He laughs, delightedly. He's very jolly company, sarcastic and swishy and vain, and unexpectedly argumentative about sex and politics, as we shall see. He's probably tired of being called "mischievous", but has a face that expresses all manner of omnisexual wickedness.

Encounters with mad city-folk is good exercise for a man in the middle of a mad project – Macbeth at the Glasgow Tramway. This challenging production is set in a mental hospital, where Cumming plays "a guy in a state of psychosis". Shortly after being admitted, he starts to enact the Scottish play and does all of the characters – thane, king, deranged wife ("Lady Macbeth is the first person in literature to suffer from OCD"), the witches, Macduff – virtually everyone bar the ghost of Banquo. It's a demanding performance that's left him covered in bruises, which he reveals in the street, hoicking up his matelot T-shirt.

"The first couple of days I did the show, I woke feeling like I'd been beaten up. I asked my assistant: 'Can you watch the play for me and try and work out how I got my bruises?' Because when you're doing it, you don't have time to reflect on anything." It's a fierily intense performance that's drawn loud praise and personal confessions. "I get letters saying, 'Never has mental illness been so accurately portrayed'. Well thanks, I think. After the show people want to come up and talk about their own mental condition. Of course, the play is all about madness. All these visions. Madness is mentioned so often that... Oh those shoes are fantastic, Gary, where did you get them?"

Had it felt odd to be back in Glasgow, where his teenage self attended the Royal Scottish Academy of Music and Drama? "I walked past my old drama school – which is not even in the same building as it was, and doesn't have the same name as before, that's how fucking old I am – and there I was, doing Shakespeare in Glasgow, doing movement and warm-ups, 30 years later. It's really weird. I can't believe I'm nearly 50. I'm probably fitter than I've ever been, and I'm doing the most challenging thing in my life. Ooh, look at that doggie..."

Cumming's grasshopper attention span is of a piece with his professional restlessness. No actor alive throws himself into such an eclectic mix of roles and pursuits. It's not just the lack of consistency in his screen roles – in the mid-1990s, he went from playing the baddie Grishenko in the James Bond film Goldeneye, to playing Mr Elton in Jane Austen's Emma, to appearing in Spice World, to playing the hotel desk clerk in Stanley Kubrick's Eyes Wide Shut – or the fact that he alternates them with serious theatre roles (Hamlet, Mac the Knife in The Threepenny Opera, the MC in Cabaret, for which he won a Tony on Broadway). It's everything else. In recent years, he's written a novel, Tommy's Tale, and several articles for Marie Claire, Modern Painters and The Wall Street Journal, launched a range of scented bath and body lotions, subtly entitled Cumming, had his photographs exhibited in a gallery...

This thing of being a TV presenter, I say. Is it part of a grand strategy to diversify in case everything dries up? Or is it some inner compulsion? "It doesn't feel like a compulsion," says Cumming. "I've always done it. In my first year at drama school, I did this kids' show called Let's See. I'm host of PBS's Masterpiece Mystery. Diana Rigg and Vincent Price did it before me. I stepped into Dame Di's shoes!" He beams. "I think the older you get, the more open you are to the world. Everything breeds itself. People think, 'Maybe he'd like to do that'. Other people see it and ask you to do something else... I don't feel I'm a compulsive person. I multitask. I'm really well-organised, and I have lots of people to help me."

Did I mention the record? Stand by for Alan Cumming, pop diva. "I had my one-man cabaret called I Bought a Blue Car Today, from which there was an album. And I did a single recently. You know Adele's 'Someone Like You' and Lady Gaga's 'The Edge of Glory' and Katy Perry's 'Firework'? I was listening to them in a club one night and thought, they're all the same song, chord structure and everything. So I did a mash-up of them and made a single of it." His hazel eyes take on a dreamy look. "It's really lovely..."

In America, he's best known for The Good Wife, about a woman struggling to keep her family and professional life together, after her state-attorney husband is jailed following a sex scandal. Popular, award-winning (and available here on More4) it's in its fourth series. Cumming plays Eli Gold, the errant husband's abrasive campaign manager – a kind of Jewish Malcolm Tucker – as he fights his way back to power.

"I joined the show two-thirds of the way into the first season," Cumming explains. "I had no idea what I was doing. They asked me, and I said I don't want to [do it]. I read the script quickly, and it was hard to understand what was going on. But my managers and agents were, like, you should do this." Why did the producers approach him to play a rude Jewish-American policy adviser? "Would it be because I'm a fabulous, top, international award-winning actor?" says Cumming, deadpan. And did being a rude, Jewish campaign manager come naturally to him? "No, but neither does being a Smurf or a king. What I think about Eli is that he's so not me, it feels fantastical. Being in an office – I don't have access to that experience. But I understand jealousy and passion and revenge, all those things – they're all themes you get in Macbeth."

Then I ask something that touches a jangling nerve in this essentially unserious man's nerve system. You have, I say, a high profile as an activist for gay and lesbian rights and for Aids charities, you're a publically declared bisexual, you've won awards for campaigning against homophobia; Eli Gold in The Good Wife is straight and has affairs with women. Is it getting easier for gay male actors to get straight roles in American TV and movies? Are producers no longer concerned that they won't be convincing to audiences?

"I find that all... If you're not convincing as anything, you're not convincing," says Cumming. "Your sexuality or beliefs are sometimes relevant to the role you're playing, and sometimes not. In Eli's case, they're absolutely not. I have affairs in the series. If people didn't believe it... I mean, I play Macbeth but nobody says, 'Och, he never murdered anyone, how dare he act in this'. You know what I mean?"

But Alan, I say, when millions watch your fictional character approach a relationship with an actress, they devote some emotional energy to hoping it'll happen. Producers used to worry that they wouldn't believe in the relationship if one of the actors was gay. Don't they still? "I've been shagging away on screen this season," says Cumming crossly. "I've never seen it as a worry or a problem or an issue. Even to speak about it smacks of homophobia. There's a hint of homophobia even in the question."

In my question? "No, the question in general. You remember Anne Heche in Six Days Seven Nights?" People supposedly found Heche's on-screen attraction to Harrison Ford problematic because she was gay. "If she hadn't been going out with Ellen [DeGeneres], nobody would have said that."

Exactly, I say. That's why Hollywood is crammed with people who are gay and in the closet because they're afraid of rejection at the box office. "The point is," says Cumming, "that talking about it only adds to the homophobia. It should be not worthy of talking about. Ooh, look at that wall..."

We cross the road to check out a beautiful mural of a bird by the Belgian artist Roa. After a minute, Cumming returns to the subject: "I don't think people refuse to see someone in the cinema because they disagree with their sexuality or politics. They don't like you because you're not convincing enough, or not good enough or not to their taste. But those things are separate and should remain so."

He's signed up for The Good Wife for three years. It wasn't a hard decision at 47. "You know what? It shoots in New York, where I live. It's the best-written material on TV. It's hugely popular. I play a great character. I don't work every day. I'm able to do my weird little arty things on the side. I'm able to have a life where I see my friends on a regular basis. I don't have to fly round the world all the time. The pay's OK, and so's the security." So there. And he gets a summer holiday each year – or summer "hiatus" as it's quaintly called. "During my hiatus from The Good Wife last year, I did a movie in which I played part of a gay couple trying to adopt a Down syndrome child. The year before, I did a mini-series in which I played a transvestite. Every summer, I run and do something as far removed from Eli Gold as possible."

So life is pretty agreeable for this Scotsman in New York. He and his partner, Grant Shaffer, a graphic artist, live in Manhattan's East Village with their pet dogs, Honey and Leon. Weekends are spent at their retreat in the Catskill mountains, where they invite hordes of friends to stay. But Cumming has retained a hold on his Scottish roots, and is a passionate advocate of Scottish independence.

"I go home to Scotland several times a year. I'm going to buy a flat in Edinburgh. I want to be close to my mum. I'm in Scotland more than I am in London these days. And I'll be able to vote in the referendum in 2014."

Why is he so keen on independence? "In the past 15 years, Scotland has had its own parliament and it's been a huge success. Scotland's become its own country, economically , socially, culturally – they've been able to self-govern to an extent and the spirit of the country's changed because they can't blame England for everything. Scotland has looked out to the world in a different way, and it's now looked on differently. It's been such a success – why not keep going with it? We don't like the way Westminster is still dominating the conversation."

He was annoyed by a moment on BBC's Question Time, when Scottish devolution came up. During a heated exchange, Lord Forsyth, former Scottish Secretary, suggested that his fellow guest, Cumming, didn't understand the debate, "because you live in America". Cumming is still furious. "All that shit. I live in Britain, I'm a British citizen, I pay taxes. I had to say all these things on television [in my defence]. Even if it weren't true, how dare he say I can't have an opinion? I'm from Scotland, I care about it, I come and work there, I've been working for the National Theatre of Scotland playing the king of Scotland. I have a vested interest in the place and I have opinions. It's easy to slap down celebrities. But with such venom – is this what we want in the new Scotland? No freedom of thought?"

Uh-oh. Is this the voice of a politician-in-the-making? It could be the sound of Alan Cumming – stage, screen and TV actor, writer, producer, director, presenter, singer, photographer and perfume impresario – adding yet another string to his bow. Just as long as he doesn't get distracted...

'Urban Secrets' is on Sky Atlantic HD, Thursdays at 8pm