Actor Matthew Marsh launched his acting career on a canalboat, touring the country’s waterways with specialist company Mikron, an experience he followed up with more than 30 regional productions over just five years at Lancaster’s Duke’s Playhouse and Manchester’s Library Theatre.

In London, Marsh spent many years off and on at the Young Vic where his credits have included The Jail Diary of Albie Sachs, Stags and Hens, Hamlet, The Crucible, Julius Caesar, Who’s Afraid of Virginia Woolf?, Comedians, Sex Please We’re Italian and All My Sons. Amongst his early West End credits were Marya, Last Yankee and Tolstoy.

Marsh’s screen credits include: The Commander, An Affair in Mind, Red Dwarf, A Touch of Frost, Death of a Salesman, Service, Hotel Babylon, Surviving Disaster, Belonging, Return of the Dancing Master and Wall of Silence on TV; and The Fourth Protocol, Mountains of the Moon, Dirty Weekend, Smilla’s Sense of Snow, Bad Company, Miranda, Quicksand, Spygame, Bad Company, O Jerusalem and An American Haunting on film.

In recent years, Marsh has been seen on the London stage in The Goat, or Who Is Sylvia? (Almeida and West End), A Buyer’s Market (Bush), The Little Foxes (Donmar Warehouse), Conversations after a Burial (Almeida), Us and Them (Hampstead), The Exonerated (Riverside Studios) and Michael Frayn’s Copenhagen (National Theatre and West End).

This month, Marsh has returned to the National to star in the world premiere of The Overwhelming, which marks the UK debut for the young American playwright JT Rogers. Out of Joint artistic director Max Stafford-Clark directs the drama in which Marsh plays an American academic who, while researching a book, moves his family to Rwanda on the eve of the 1994 genocide.

Date & place birth
Born in London on 8 July 1954.

Lives now in
I’ve been in Muswell Hill (north London) for the last 18 years.

What made you want to become an actor?
I didn't really. I didn’t train to be actor. I was going to be a cricketer until I was 15 then I was going to be an academic, then I went to university to do a degree in English Lit and decided not to be an academic after about a term. I got into doing comedy at university. We went to the Edinburgh Festival a couple of times,and we wanted to bring a show into London but there was no comedy circuit then so we all went off. I went to America and Mexico for four months just travelling around. When I got back, I think I was applying for journalism and other jobs when I saw an advert in Time Out for an acting job. I went and knocked on the door rather than writing and the director's wife opened the door. I kind of schmoozed her for about five minutes and she said, oh come back next week and meet my husband and he'll audition you. So I did and that was a nine-month gig with a fringe company which resulted in a full Equity card,which was important then. I don't think I'd have even got an audition if I'd written. I can't remember at the time thinking, yes,I'm going to be an actor. It was just something that came up and that's it really, I haven't done anything else since.

First big break
That woman opening the door. It was a theatre company called Mikron that travelled round on a canal boat for six months of the year doing shows in pubs by the canalside, sort of musical documentary shows about canals! I helped research and write one of their shows and wrote five songs for it, then I had six months living on a canal boat with five other people and travelling 1,800 miles and doing six month's worth of shows. Once you've performed in a tiny pub to 120 canal enthusiasts four feet away from you … it's a good baptism of fire.

Career highlights to date
I think I've just been incredibly lucky because there are very very few jobs I can think of as being bad experiences, even the big flops. The experience of getting through a flop is a good experience sometimes - you'd be pretty bloody miserable if everything you did was universally rewarded. I did ten plays in six years at the Young Vic in the mid-Eighties. That was great to be part of one particular theatre and keep going back. The last six or seven years I've just loved every job I've done.

Favourite productions
Copenhagen was such a fantastic play, such a demanding play. I was on stage virtually all the time - 170 odd shows and I was never bored for a second. I've got a very low tolerance for boredom. Long runs don't appeal to me. I don't want to put anyone off offering me a long run, but the buzz I get is from constantly moving on and working with new people and new scripts.

Favourite co-stars
This is going to sound trite, but this company at the moment is a terrific company. It's exciting to work with a group of actors I've never worked with before. With the exception of one or two, I wasn’t even really aware of their work. It's nice too because there are so many nationalities. I really loved being on stage with Jonathan Pryce in The Goat - watching in rehearsals the way he builds and builds very slowly on his role, and the way he is always open to what other people are saying and attempting fresh things and being very responsive and challenging at times. Another one was Ian Bannen in All My Sons at the Young Vic. Ian played my dad and - I don't think he would mind me saying, may he rest in peace – that he was a bit shaky on the lines when we opened. But there were some nights when, in individual scenes, something would happen to Ian, and suddenly it was like seeing somebody even more three-dimensional than any other actor you've been on stage with. Another is Donald Sutherland, who I worked with about 18 months ago on a film called The American Haunting. I loved being around him.

Favourite directors
Well, I have to give a special mention to David Thacker because he directed me in over 30 plays, about ten at the Young Vic and then 20+ at Lancaster between 1979 and ‘90 or something like that. So I learned an awful lot about acting from working with him. Since 1990, I feel like I've just worked my way through some of the best directors in the country. Without wanting to sound as though I'm asking for these people to employ me again, I have enjoyed working with all of them.

Favourite playwrights
I love the American playwrights: Arthur Miller, Tennessee Williams, Eugene O'Neill, Edward Albee. And I think JT Rogers has a long career ahead of him. Apart from that, until about 1990, all the plays I did were the classics, which was great because over a ten-year period or something, I did about 35 plays. Since 1990, I sort of made a slightly conscious decision to just do new work. I think The Little Foxes (at the Donmar Warehouse) is the only one I've done since then which was not a British premiere or a world premiere. I absolutely love knowing that nobody in the audience has seen this before, that you're working on a script that no one else has attempted. That to me now is a major kick I get out of working in the theatre, knowing it's a first for everyone there. Another playwright I should mention is Michael Wall, who died in the early 1990s and was one of my closest friends. He wrote Amongst Barbarians and Resistance, which I did at the Old Red Lion in 1994. It was terribly sad that his talent got cut short.

What’s the last thing you saw on stage that had a big impact on you? And the first?
I don't go to the theatre as much as I should, maybe six or seven times a year. Death of a Salesman was incredible. And, it's going back a bit, but I did love Shockheaded Peter. The first? I remember seeing Olivier when I was kid in Long Day's Journey into Night, which was directed by Michael Blakemore. So when I got to work with Michael 20 or 30 years later (on Copenhagen), it was a real thrill.

What would you advise the government to secure the future of British theatre?
The increases in funding over the last seven or eight years should continue and be upped. Of course subsidy can't cover every person or company who wants to be in this business, because we are a very oversubscribed business. There's always going to be an element of the jungle out there. And sometimes starting out with nothing does, ironically, generate some incredible work. Subsidy doesn't necessarily mean excellence, but you need a generous level of subsidy to keep a lot of the really great theatres and companies going.

If you could swap places with someone (living or dead) for a day, who would it be?
Freddie Flintoff, virtually any of the days in last summer's Ashes.

Favourite holiday destinations
I used to have a house in France, but I’m not very good at holidays. For me, one of the best things about being an actor is travelling for work. I absolutely love filming abroad. Being in a foreign country for six to ten weeks, knowing you've got to work for 60% of the days but then you've got the rest of the time to explore, that's my ideal holiday, a working holiday.

Favourite books
I don't read much fiction any more. That's partly Raymond Carver's fault. I loved his work so much that it made a lot of other writers seem florid. I read a lot of non-fiction now. There's one particular book I read a couple of years back called In Siberia. I hated geography at school but it’s absolutely essential. Even as an actor, I think it's crucial: if you're filming, don't make any decisions until you know where you're filming and what the dynamic is. That book about Siberia (by Colin Thubron) just opened my eyes to a part of the world and a history I was completely unaware of.

Why did you want to accept your part in The Overwhelming?
Because it's the best new play I've read in a long time. It's about Rwanda. I'd seen a couple of films about Rwanda so I was very interested in the subject, but this play takes a completely different angle in that it's set just before the genocide. It's an extraordinarily powerful and intelligent play in which an American family go to Rwanda with very good intentions and find themselves in a situation that's rapidly changing and that they don't understand it, and they try to get involved, they try to help as the situation’s worsening there. So the play manages to be very specific about the individuals involved, and the Rwandan characters as well are beautifully drawn on all sides of the conflict. It's a wonderful play about that whole dilemma which is with us all the time: about how we in the developed world can interact or respond, help or hinder what is going on in a third world country.

What research did you do for the play?
Before we started, I read the Canadian UN General's book called Shake Hands with the Devil about his experiences and frustration about trying to intervene in Rwanda because of the lack of will of his bosses back in the UN and the international political community. Max Stafford-Clark made us do a lot of research so I've read a couple more books since then and we've had five or six people come to talk to us, journalists who were there and several Rwandans who were very personally involved in what went on in 1994 and beyond. So, yes, as a company we know quite a bit about it now.

What was the most shocking thing you discovered?
Certainly the failures of the international community to acknowledge what was going on was shocking. When they did decide to kind of get involved, they made incredible mistakes. They poured a load of humanitarian aid into refugee camps which probably had 20% to 25% of the chief killers there. So the killers, supported by international community, ran the refugee camps, full of corruptions, stealing all the aid, and then they kept attacking back into Rwanda. Using a single historical event like this gives you a way into the wider problems and history of that whole region and the ongoing problems now which we don't see on the news. All we see on the news is occasional starving or dead bodies and we don't understand what's caused it, we just think, oh that's Africa, that’s what happens. There are always reasons why it happens. This is getting like Panorama, sorry!

Do you remember the coverage of the Rwandan genocide at the time?
I can't honestly say that I registered it more than as another African tragedy because all you see is sporadic television coverage and the isolated newspaper reports. Fergal Keane has written a book about Rwanda and he goes back all the time. He and Lindsey Hilsom, who was there for Channel 4, came to talk to us. They read the play and thought it was fantastic for telling the truth, which hasn't been told in the films which have tended to focus on the surface rather than what was going on below. That was great to have the endorsement of people who were actually there at the time.

Do you think it is individuals’ personal responsibility – or that of the media – to keep us better informed about such situations?
I think it's a bit of both. One of my bugbears at the moment is that the news is so driven by where you can get a camera, and what a camera wants to see is violence or the after-effects of violence because that is somehow grabby, it has an immediate impact. I think that actually distorts what we receive about what’s going on in foreign parts of the world. It makes you feel you don't have to understand because you can say, well, we've seen it.

Do you have a favourite line from the play?
I don't have a particular stand-out line. All the characters have good lines. That's one of the best things about the play: all the characters have powerful arguments and very strong reasons and motives and fears which drive them and make them act in the way they do.

This is the fourth American you’ve played in a row on stage.
Yes, and I think it's my 23rd American overall professionally on film, TV and stage. I think I also did one on the radio. Over 29 years that's less than one a year if you spread it out. I've always loved playing Americans. I have a facility with some accents. My uncle was in New York in the Sixties. I remember he brought back an American comedy, and I used to mimic the voices because I found them so brilliant. I also got into Lenny Bruce when I was in my twenties. He did hundreds of different voices and I mimicking them too. I think once you've done American and people have seen you, they will consider you for other American parts. I don't only do Americans. It's slightly strange that I've done four in a row now - it was a Russian before that.

What are your future plans?
The Overwhelming goes on until October. I've been doing The Commander on television on and off and I think ITV has asked for three more two-hour films, so that will probably happen. I’ll need to get some money back that I've lost. That's the problem of working in the theatre - it's not enough money, and I have a large family. I've raised five children. The reality is, unless you're a star in a West End show, you can't earn a decent wage in the theatre. I like filming as much as I like working on stage, I love both of them. I still hanker to be a comic actor, and I'm a frustrated song and dance man. One of the happiest jobs I did was Privates on Parade in Manchester about 20 years ago. I'm really into mucking up dance routines. I'd love to do some more musicals.

- Matthew Marsh was speaking to Terri Paddock

The Overwhelming had its world premiere on 17 May 2006 (preview from 9 May) at the National’s Cottesloe Theatre, where it continues in rep until September when it embarks on a five-week tour, visiting Oxford, Leeds, Southampton, Liverpool and Manchester, where it concludes on 7 October.