Brian Cox is an amazing chameleon. I've wandered round the Soho café for a good 20 minutes before I realise the unassuming man in the corner is one of our finest British film actors. Grey hair tucked under a Panama hat, he looks elderly, almost frail at 60. Can this be the man hailed as the embodiment of evil when he played the serial killer Hannibal Lecter in Manhunter, the first screen adaptation of Thomas Harris's novels?
I introduce myself, Cox removes the hat, and visibly loses 20 years. In fact, as our interview continues, and he fixes me with those deep-set blue eyes, he gets younger by the minute. Partly it's his energy, but he also has real enthusiasm for every aspect of popular culture, from Green Wing and Desperate Housewives to site-specific theatre.
Cox was never a matinee idol. With a stocky body and wide, mobile face (described by one reviewer as "an amorphous lump of clay") he specialised in playing flawed everymen. But that training as a character actor has paid dividends. These days he steals every Hollywood movie he's in. Directors from Spike Jonze and Spike Lee to Woody Allen are queuing up to work with him. Even the Farrelly brothers, masters of gross-out cinema, cast him in last year's The Ringer.
With homes in LA and London, he's entitled to play the movie star, but there's no sign that Cox, a Scot of Irish extraction, has forgotten his roots. "I come from being cannon fodder for the English," he laughs.
These days Cox's life is full. Married to his second wife, the 37-year-old actress Nicole Ansari, he has two children under five. In addition he has two grown-up children, Alan, an actor, and Margaret, from his first marriage.
He's back in London for six months starring in Tom Stoppard's Rock'n'Roll. Next month, he turns up as a lead character in the third series of HBO's hit Western drama, Deadwood. Then there's Augusten Burroughs' memoir, Running With Scissors, in which he plays a psychiatrist opposite Gwyneth Paltrow.
You sense Cox relishes such diversity. For a time it looked as if he would be pigeonholed as Hollywood's resident villain. After Lecter and Hermann Goering in Nuremberg (which won him an Emmy), he stole the show as the baddy in X2: X Men United and The Bourne Identity.
According to Bourne Identity's director, Paul Greengrass, "Brian brings all of the colours anyone could ask for in a plausible adversary; he can be sinuous and he can be bullying; he can be cunning and he can be self-dramatising; he can be pathetic and frightening and sinister. There's a whole spectrum in between the poles of black and white that he inhabits brilliantly."
The turning point came in 1986 when he was cast as Lecter in Michael Mann's Manhunter (five years before Anthony Hopkins played the character in The Silence of the Lambs). Mann's casting director spotted Cox on stage and offered him the part. It was only Cox's third film. He was on screen less than 10 minutes, but he exuded an electrifying menace.
Murderers are fascinating, he insists. "The demonisation of people like Lecter makes us feel safe because we can all think it is not us. But if we are really honest, it is us. It isn't a bogeyman but an indisciplined individual at the moment when he becomes psychotic."
In fact Manhunter nearly didn't happen. The producer went bust and the film didn't get a proper release. But after the success of Silence of the Lambs, it was rediscovered and became a cult movie. Cox jokes that Hopkins must get thoroughly sick of critics raving about his performance whenever they're supposed to be reviewing Hopkins.
But then as an actor, Cox is always delving below the surface: giving humanity to flawed characters. In Michael Cuesta's controversial 2001 film, L.I.E., he played an extraordinarily charming and plausible child molester.
"I don't judge characters," he says simply. "It is imperative to empathise, though not to sympathise." All human beings have certain things in common: what interests him is finding the differences - the predilections, private weaknesses and shadows.
The most memorable thing about Cox is his voice. He can do camp and he can do terrifying. We think of him as a film actor, but he has f had an impressive stage career too. Best known for playing King Lear at the National and Titus Andronicus at the RSC, he starred in Conor McPherson's Dublin Carol in 2000.
And now there's the Stoppard. "It's so fascinating to do a new play by an established British writer, who himself is going through a personal renaissance," Cox enthuses. "It's less flash than Tom's previous plays; there's a new directness." Spanning the history of Czechoslovakia from the Prague spring of 1968 to the Velvet Revolution, Rock'n'Roll is Stoppard's semi-autobiographical take on Communism, love, Englishness and rock music. Rufus Sewell plays a young Czech studying philosophy at Cambridge who is befriended by an English academic (Cox).
Cox is splendid as the dyed-in-the-wool Marxist ("I'm like the last white rhino," he bellows in the play), spouting materialist theories of brain function, but unable to relate emotionally to his wife and daughter. He's a shamelessly unyielding alpha male, but Cox invests him with real pathos.
Rock'n'Roll is a play about the loss of idealism. "It's an incredibly humanist piece but what it deals with is how man lets down every idea he sets up. It's very relevant, especially now when you see mistrust in religions, mistrust in political parties, how parties have moved away from their very principles, and how New Labour has become retro-Conservatism," he says, banging the table. It's a subject close to his heart. He talks earnestly about the shortcomings of the British healthcare and education system and condemns Blair as a "moral pragmatist", losing support after a disastrous war.
The youngest of five, Cox was brought up in a poor Irish-Catholic family in Dundee. He was nine when his father died of cancer. His mother developed a compulsive obsession with cleanliness, tried to commit suicide and never recovered from electric-shock treatment (she died in 1973). Brian was brought up by aunts and older sisters.
"Childhood is one of the cruellest times of your life," he acknowledges. He became the class clown. "That's one of the reasons that my acting is the way it is, because I always look for the humour in what I do." Cinema - in the form of James Dean, Marlon Brando and Jimmy Cagney - was his salvation. He left school at 15, joined the Dundee Rep, then headed for London where he carved out a stage and TV career (everything from Z Cars to Play for Today). His marriage to actress Caroline Burt was fraught with worries about money. They lived in Fulham and took in lodgers.
Cox's marriage ended and he chose to work in Britain to stay close to his children. In 1995, with Manhunter a calling card, he took off to America. "I wanted to make up for all the lost time." He played Daphne's dad in Frasier (which earned him an Emmy nomination) and is still passionate about comedy. "Green Wing is doing stuff that's astonishing. You go, 'This is truly remarkable work'. It's got scope, it's big on style and content. My wife is German and she can't believe Green Wing."
Cox once declared, "I'd rather do bad movies than bad television because you get more money for it." But he's been lured back to the small screen by Deadwood. He credits the show's executive-producer David Milch (who also created NYPD Blue). "He's extraordinary, a real powerhouse, and it's all his vision."
Deadwood is an anti-Western. Set in the 1870s in Dakota Territory, it charts Deadwood's growth from outlaw camp to town. Cox thinks it's a brilliant exploration of western capitalism. "It shows that America is still a culture that has only just come out of chaos in the last century, and in that sense the show is very allegorical."
Cox plays an eccentric producer and theatre owner. "My character comes in to provide the notion of culture which historically always turns up in a society after the fucking and the drinking. After a while the satiation of man's appetites isn't enough. Ultimately people feel, 'There must be something more'." He loved working with Ian McShane who plays the show's anti-hero. "I understood Ian's stories, and he understood my stories because our tradition is the same. But also we're both Americanophiles"
He praises the way American TV keeps pushing the envelope. "I think that's because it's primarily writer-led and fairly egalitarian." He claims British TV drama, once the finest in the world, lags behind, because it's based on people being told what to do and shut up.
"Fifteen years ago, Alan Bleasdale was trying to take on the role of writer-producer the way Paul Abbott does now, and he was vilified for getting above his station. Even writers like Dennis Potter either worked to patronage or the wonderful old-style BBC producers like Ken Trodd who were part of the feudal culture. Everyone was looked after, it was done on a nod and a wink, but it wasn't actually woven into the fabric of the industry. In America they say, 'How do we make what we want to write and make it successful?' Look at something like Desperate Housewives. You have this man who sat down and wrote a satire, which is ostensibly what Desperate Housewives is, but when he went to pitch it, he called it a soap opera, and everyone went, 'Oh, fine'. It happens time and time again because great American TV is so subversive."
Cox has a horror of posh. Even though he was terrific as the father in Allen's Match Point, he found the upper-class accent far harder than playing American. "The nice thing about living and working in America is that it's a fundamentally egalitarian society. It doesn't matter what school you went to."
He has no time for the new-model Conservative party. "It's the same old crap in a different form, and people don't see it. Mind you," he smiles, "I just come across like some old lefty. People say: Try another tune, but all my life I've always been an anglophile, too. I moved to London as soon as I had the money to come down, and it was a great liberator for me, although as I get older I have more and more connection with my roots."
He'd like to play softer roles. "I don't see myself as this rather fierce, authoritarian-type person." I'd like to see him cast as a romantic hero: he can be powerfully sexy. Cox's own role models are Robert Duvall, Gene Hackman and Bill Murray. "I managed to carve a career going in that direction so I feel very blessed because I did it after 50, when most people curl up their toes and decide that's it."
'Rock'n'Roll' is at the Royal Court, London SW1, until 15 July, then at the Duke of York's, London WC2, from 22 July to 24 September. 'Deadwood' starts on 6 July at 10pm on Sky OneReuse content