Damian Lewis is sitting opposite me, drinking tea in a wood-panelled library in a discreetly opulent Central London hotel. With his clipped Old Etonian accent and understated self-confidence, he seems the epitome of Englishness. Which is why it’s surprising that so many of his highest profile roles have been Americans.

His latest drama, Homeland, is no exception. Lewis plays US Marine Sergeant Nicholas Brody, who has been held as a prisoner of war for eight years by Al Qaeda. On his return, he is feted as a hero. But CIA officer Carrie Mathison (Claire Danes) believes that, far from being an All-American patriot, he has been turned, and represents a grave threat to national security.

Here, the charming and affable Lewis talks about the series, his career to date, and how he’d give it all up in a heartbeat just to change one single moment from his past.

You had a great education, went to Eton, and at the end of it, you turned around and said to your parents that you wanted to go into the most capricious business imagineable. Parents dread their children wanting to act. How did yours react?

They were brilliant, and oddly supportive. They had seen me on stage at that point. A group of us put on a play at school, and my parents saw me, and I think they decided that it wasn’t going to be a complete waste of time. And so in the last two years, when I should have been working for my A levels, I decided that I wanted to go to drama school. I’d stopped working, and my shocking A level results reflected that. So I was only going to go off to a not very exciting university anyway, and so I went to drama school. My mum said “Go, with our blessing.” And what she really meant was “And that means you can stay at home with me for another three years.” I grew up in London, so I lived at home throughout drama school. It was a very un-studenty three years. I went back to a nice family house every night where, if I was lucky, mum had left out a fishcake.

You went to The Guildhall School of Music and Drama. Have any of your contemporaries from there gone on to stardom?

There was a very rich seam of talent all around us. Joseph Fiennes was a contemporary of mine. Ewan McGregor was in the year ahead, Daniel Craig was in the year ahead of him. Just in front of them were people like Ben Chaplin and Rhys Ifans. Dominic West was just behind me.

And from there you went on to the RSC. Was that a valuable part of your education as an actor?

Yes it was. It gave me a campus life that I hadn’t had. It was a bit like going through another training – you’d have voice lessons and verse lessons, and you’d rehearse all day and perform all night. And you just happened to be living in a small wendy house of a 17th Century workman’s cottage right next to the River Avon, with Shakespeare’s graveyard 300 yards one way and where he lived a couple of miles the other way. It was a rather extraordinary, rarified existence for a year. I loved it. And I would imagine, having visited Oxford and Cambridge many times to go and see my friends who were studying there, and I played cricket there quite a lot *cough* – where I scored a century – (the only one I’ve ever scored, and it was against a team called The Grannies!) I imagine our existence [at the RSC] was quite similar, just living in these beautiful, bucolic surroundings.

Jumping forward a bit, somewhat out of the blue, you land the lead in the most expensive TV show ever made [Band of Brothers]. That must have carried quite a lot of pressure with it.

It was totally out of the blue, because they didn’t know me from Adam. I think part of the reason I got that role was because he was a 1940s war hero, and even though he was an American, there was something old-fashioned about him, and upright. I think they felt they might find him in England, in a stiffer, more upright actor than a cool American hipster. It was a big sea change, and it was a huge hit, although it had a pretty inauspicious start, because the second week it was on air, 9/11 happened, and people’s appetite for death and destruction and a rather realistic vision of war – it just wasn’t what people wanted at that point. But it sort of regenerated itself. It’s the most extraordinary beast, Band of Brothers. It still feels like it only happened last year, because people are still so connected to it. It’s ten years ago now, and people are still watching it for the first time, or for the 100th time, and people still want to come up to me and talk about it. Armed forces in Afghanistan watch it as inspirational tools, soldiers are actually taught it for lessons in leadership. And the manoeuvre that Winters perfected the day after they landed at Normandy, when he took the four 88s shelling the beach- that’s taught in West Point. I was filming in Crete about five years ago, and the US Navy landed, and they’d been watching it. It’s got an extraordinary reach. And I did feel pressure. There’s a huge responsibility – as there always is if you’re playing somebody who’s alive – to represent him well. And as Tom Hanks said, as we started the whole endeavour, on our first day at boot camp, “Don’t think of this as making a piece of TV. Think of this as an historical document. That’s what we’re going to try and recreate here.” It was brilliant.

Where does Band of Brothers sit in terms of work that you’re proud of, and what else is up there?

It sits right up there; it’s certainly the thing that I think I’ve done that’s had the biggest profile. One of the things that’s had the smallest profile is arguably what I’m most proud of, which is a small independent film called Keane, which I made about four years ago. I’m very proud of The Forsyte Saga, I enjoyed that enormously, and an Ibsen I did at The National Theatre, Much Ado About Nothing for the BBC, I loved doing that. And I’m extremely proud of Homeland.

Moving on to Homeland, what attracted you to the role?

After my experience on Life, which I loved, but it was at quite a lot of personal cost, from a family point of view – that sounds a bit melodramatic, we’re all still together! – but it was long hours working with Helen sitting in the house with the kids. I wasn’t prepared for quite the workshop hours you work on some American TV shows. So I said to my agent ‘Only if it’s extraordinary, and if it’s on Cable TV, so it’s a five-month commitment rather than a ten-month commitment. [Cable series tend to be 12 episodes as opposed to 24 on networks.] Unbelievably fortunately, this thing came my way, and I very nearly said no to it, for all the reasons I’ve just explained. But it was really compellingly written. The pilot – which was all I read – had political ambition, it was psychologically detailed and specific, dark in places, and so ambitious. It was tapping into conditions that interest me – Post Traumatic Stress Disorder and men returning from war, and bipolar disorder in Claire’s character. While tackling these rather serious issues, it also managed to be a page-turner. And it also managed to be a political show at the same time, posing the question ‘In our pursuit of terrorists, have we gone about it in the right way?’ It just seemed brilliantly representative of a slightly uncertain, paranoid world we live in now. It’s a bold claim for one hour of TV, but I spoke to them, and they convinced me that these were all themes that they wanted to pursue. And they sustain it. They’re brilliant, and I’m unbelievably lucky to be working with them. Thank God I said yes to it.

Is it quite attractive playing a character who’s so ambiguous, who might be good, or might be very, very bad?

Yeah, ambiguity is a complex thing to play. It can leave you being a little unspecific, if you’re not careful – if you’re consciously vague, and you then allow the audience to project onto you. But if you’re doing it well, the reverse is true – you commit yourself to decisions totally, and it’s just about how adroit you are with your changes, that is in the end what creates the ambiguity. You have to be lightning quick and nimble, there’s a mental and imaginative agility in the performance which is really fun. It’s a challenge – there are so many things to play, and if you try and play everything at once, then it’s a bit of a pudding, so you have to make specific choices and then just change on a sixpence. Another thing that really appealed to me is it’s very subversive. It’s very controversial to have a US Marine, who is as great a symbol as anyone or anything you can think of that upholds our Western freedoms and our beliefs, and goes and fights on our behalf all over the world. To have one of those people ‘changed’ is very controversial.

How was it working with Claire Danes?

Lovely. She’s whip-smart, and extremely committed and focused. Quite disconcertingly, sometimes. She can be in this extraordinary scene, and the director says cut, and before you’ve turned around, she’s walking back to her chair and just out of character. She plays ‘Words with Friends’ endlessly, which is that interactive Scrabble game. She’s always got about five or six games going on with different people around the world. It’s her way of relaxing. She’s got half the crew doing it with her as well. She’s just lovely. I love being in scenes with her, it’s thrilling.

The drama touches on PTSD, terrorism, death, torture and mental illness. It’s not a knockabout comedy. Does that affect your mood during filming? Do you take any of that home with you?

No, I don’t take work home. Stay an American all day long, that’s one thing I do do. It’s too confusing to switch in and out of accents. So I go to work as an American, and until my make-up’s taken off at the end of the day, I remain that way. And then I actually switch off from work alarmingly quickly. I have to rev myself up quite a lot to go back into work, because I’m quite good at down time.

Homeland has been described as 24 for grown-ups. What do you make of that?

I think the parallel with 24 is inevitable, because Howard [Gordon] is a co-creator on this, and had run 24 for the last four or five seasons – he took over from Joel Surnow. It’s not really 24. It’s far more of a psychological, political drama – I think the paranoia plays much more strongly. Just the style in which it’s filmed is very different. It takes its time, it allows it to breathe, whereas 24 was a high-octane, crack-like experience. It made me just feel extraordinarily uneasy, watching 24, it was a very uncomfortable feeling. I think Homeland is too, because of the subject matter, but there’s an enjoyment in just being able to sit in things a bit more. I think this allows you to do that.

Is it true you used to practice being interviewed by Wogan in front of the mirror at the age of ten?
I did. And now I’ve been on Wogan. Finally! I did his radio show.

The ten-year-old you craved that fame and adulation. Now you have it, how does it feel?

It sounds awful, doesn’t it? I’m not very good at just sitting and considering. I’m always on the charge a little bit. But sitting and reflecting now, I suppose it’s quite romantic, when you put it like that. Yeah, I did used to do that as a ten-year-old. When I couldn’t sleep, I would get out of bed in my pyjamas and turn on the light in the bathroom upstairs and just talk in different accents and pull faces in the mirror, pretending I was being interviewed by Wogan. He’s part of our cultural history. He’s commentated on something I’ve done before – a celebrity golf thing or a celebrity football thing I did.

Ah, the celebrity football match in which you lobbed Arsenal and Germany keeper Jens Lehmann from 25 yards, and hit the bar. How much of your success and your gongs would you give up to have that shot go six inches lower?

All of it! It was unbelievable. 70,000 people at Old Trafford. It was about the 15th minute. I was playing alongside Jamie Redknapp in the centre of the park. I just looked up and saw him inching out of his six yard box, and I just went for it. And I saw him, he had that look in his eyes as he backpedalled, saying “F*** me, I’ve been done”. And it just rattled the crossbar. The last thing Bryan Robson said to me – he was our coach – he said “Damo, you’re on Zidane. Keep yer legs closed.” And I clattered into him – I’ve always been a shocking tackler, I’m like Paul Scholes. I’m always late, and just bad at it. I clattered him. Jamie Redknapp came over and said “Damo, Damo, calm down. You can’t clatter into Zizou like that. You could’ve broken his ankle.” I thought “Alright, it’s just that the twice-world footballer of the year was a bit quicker than me!” And in about the 30th minute, we were right by the touchline, and I thought “He’s going nowhere!” And he just looked at me, and nutmegged me – straight through my legs! And the whole stand erupted in spontaneous laughter. Still, I suppose he’s nutmegged much better players than me!

Frost would like to thank Channel 4 for this interview. Homelands will be aired in the UK by Channel 4.