Dominic West's agent is holding her head in her hands. West has just been telling me how he's been offered a "a big Disney one ... by the guy who did WALL-E" and his agent had interjected that he is jinxing the job before he has signed on the dotted line. "Am I jinxing it?" he retorts. "I don't want it anyway."
He's joking of course, but it's the sort of quip that gets West into trouble – or rather generates media storms-in-a-teacup, as when he appeared to criticise the BBC for doing costume drama like Cranford "brilliantly", but not being able "to do contemporary stuff". More recently West, as one headline writer put it, "hits out over foreign stars playing British heroes". The actor had been talking about the likes of Russell Crowe as Robin Hood in Ridley Scott's upcoming men-in-tights blockbuster and Johnny Depp portraying J M Barrie in Finding Neverland. A "spokesman for West", it was reported, claimed "the comments were intended to be ironic and had been taken out of context".
It would perhaps be more accurate to say that West has a mischievous sense of humour, and is relaxed enough not to play the tight-lipped PR game. He's a bit of dream for a journalist looking for a quick story, in other words. His stare is playfully challenging when we meet to publicise his new BBC4 drama, Breaking the Mould, in which West plays Professor Howard Florey, the Australian scientist who managed to turn penicillin into a usable drug – thus saving countless millions of lives. So West is a Brit playing an Australian hero and – yes – this is a costume drama. And yet to accuse West of hypocrisy seems somehow pedantic when you meet him in the flesh. In any case, he's playing a new tune now.
"It's so rare that a really good script and a really good part come along that it makes no difference where or when it's set," he says. Breaking the Mould takes place in the Oxford of the late 1930s and the early years of the Second World War, as Florey struggled to turn Alexander Fleming's great antibiotic breakthrough into a usable drug. "I didn't know anything about this significant event and certainly had never heard of Howard Florey – and yet in Australia he was voted the greatest Australian of all time," says West. "I always assumed that penicillin had been around for a lot longer than it has. I always had a fantasy that I would have liked to have lived in the 1890s, but once I read this I realised that you don't want to have been born before 1942."
A few weeks earlier I had watched West at work on the set of Breaking the Mould, glowering meaningfully into enormous test-tubes, with the now-defunct art deco Hornsey Town Hall standing in for Oxford. "It was great playing this buttoned-up guy with a centre parting; he was very self-effacing and didn't mind losing all the glory to Alexander Fleming [played by John Sessions]. I suppose it's something everybody can relate to – not getting credit for the work you've done. In that respect he was similar to McNulty, I suppose."
Ah yes, McNulty – Detective Jimmy McNulty – the hard-drinking Baltimore narcotics cop fighting a losing battle against the city's drug-dealers in David Simon's The Wire. If West seems relaxed and in good humour it may be partly because he has returned home as the conquering hero – the de facto star of what some critics hailed as the greatest TV drama ever made ("They're absolutely right," interjects West). The actor, who claims he was second choice to Ray Winstone for the role, was to spend seven years on the show. "It all happened quite quickly – I was cast in a couple of days and then flown straight to Baltimore," he says, recalling how he was immediately put to work with real Baltimore policemen. "It was totally a culture shock for me – I was sitting in the back of the car with a murderer and hoping he wasn't going to talk to me. I was hanging out with a (cop) who had been shot eight times – three times in the head – and was still around, and I was standing around in a jacket and tie pretending to be a cop myself."
What has struck a lot of commentators is the dissonance between the working class Irish-American McNulty and the background of the actor who was portraying him. For West is that much-mythologised beast, an old Etonian. "I don't think I would have got a job like The Wire in this country because people don't think of you as a blue-collar cop if they know you went to Eton," he says. "It can be limiting in that way – but then everyone's background limits them in some way. You just have to transcend your background if you want to get anywhere."
The upbringing West has been attempting to move beyond was undoubtedly privileged. The sixth child of a large Catholic family, his father, George, owned a plastics factory near Sheffield (producing vandal-proof bus-shelters, amongst other things), while his mother, Moya, ran an amateur dramatics society where West got a taste for acting, starting with the title role in The Winslow Boy at the age of nine. But it was at Eton, under an English master called Raef Payne ("Gavin Maxwell's lover, I think") that West realised there might be a professional future in this "hobby".
"Raef Payne cast me as Hamlet and he was the first person to say 'you should do it as a job'. It had never really occurred to me that I could get paid to do this thing. Mind you, that having occurred to me at 17, I didn't actually do it for another 10 years."
In the meantime he studied English literature at Trinity College, Dublin, followed by drama at Guildhall. "At Trinity I read James Joyce's Ulysses then at drama school I read War and Peace," he says. "Those were about the only good things I did with my education."
Not quite all, because West dated his now-wife, Catherine Fitzgerald, the former Countess Durham, at Trinity – although the path of true love was decidedly in need of resurfacing. Or as he put it to an American interviewer in 2007: "She dumped me back then and she married someone else, and now we're on the rebound and we're back together."
Back together and making up for lost time, it would seem, with three children under the age of four – the latest being a mere three weeks old. West also has a 10-year-old daughter from a previous relationship with Polly Astor, granddaughter of Lord Astor. His children are the main reason he won't be doing another TV show like The Wire, he says.
"I got offered a lot of cop roles on (American) television after The Wire, but I don't really want to do any episodic television because it's a huge commitment and I've got children here and I can't really live over there for any amount of time."
He's happier to take on film roles, although he says: "The Wire was highly regarded rather than being of mass appeal, so my box office isn't particularly big. I'm not straight in at the new Batman or anything. I'd be marvellous in Batman ... "
While we await his Caped Crusader, West is doing a play at the Donmar Warehouse this autumn – Life is a Dream, by the 17th-century Spanish playwright Pedro Calderó*de la Barca ("it's about a man who's been chained to a rock all his life and then gets taken out and crowned king") – as well as series of internet adverts for Carte Noire coffee, in which West, Greg Wise and Dan Stevens will read steamy excerpts from classic romantic novels .
Expect the unexpected, then, as when, back at the turn of the century, West – having made such Hollywood films as 28 Days (opposite Sandra Bullock) and Mona Lisa Smile with Julia Roberts – suddenly joined the circus. "I was hitting an early midlife crisis," he confesses. "I saw this amazing show from Argentina called De La Guarda and I heard that they were casting for an English cast, so I had to do it. We were all flying around on ropes ... doing stunts and running up walls and grabbing people from the audience."
He thinks he might like to try a musical soon ("I once auditioned for Cameron Mackintosh and he said I had quite a good voice"), as well as get ting behind the camera. West directed an episode of The Wire and he says David Simon has promised him some directing work on Treme, his new HBO drama about musicians set in post-Hurricane Katrina New Orleans. "I read the pilot and it's amazing – it's The Wire with music. I think that will be the greatest TV show ever."
"Breaking the Mould" is on 29 July on BBC4; "The Wire" continues on BBC2