Stephen Campbell Moore & Dominic Cooper: 'We'd often not bother turning up to auditions, and go cycling on Hampstead Heath instead'

The two actors met while auditioning for Alan Bennett's The History Boys

Campbell Moore, left, says: 'We were very good at wasting our time' (Jean Goldsmith)

Dominic Cooper, 37

Since coming to public recognition on stage in 'The History Boys', Cooper (right in picture) has appeared in plays including 'His Dark Materials' and 'Phèdre' and films including 'An Education', 'My Week with Marilyn' and 'Mamma Mia!'. He lives in London

I met Stephen on stage. We were auditioning for Alan Bennett's The History Boys – 2004, I think. I was very excited about the prospect of working with Alan, though I was only vaguely aware of Stephen. But almost right away on that stage, we clicked.

It's important for a play, especially a touring play, to have camaraderie with your fellow actors. There are people who are very self-centred, who only care about what they are doing, but Stephen was the opposite of that. He was reactive, had empathy, and was terrific to work alongside.

After we finished the run, he came to live with me in Camberwell [in south London]. It was a great time to be young and in London – we were very unfocused on our work! We'd often not bother turning up to auditions, and go cycling on Hampstead Heath instead. It was a very studenty time: loads of parties, people constantly falling in and out of the flat.

But it couldn't last, and didn't. After a while we just thought to ourselves: why are we still living like this? So we moved on. But it's a chunk of my life I look back on fondly. We were both comfortable enough in ourselves, and knew that we would be fine.

We're the same age, but we are not competitive at all. I don't think we've ever gone up for the same part, but even if we did, Stephen wouldn't care much either way who got it. He understands how the business works.

Our lives have changed now. He's married, and has a baby. But we still keep in touch – properly, not just via social media. I'm not interested in giving a thumbs up if he posts a picture online, and we don't do "likes".

When we meet, we often talk about anything but work, though of course it does come up from time to time – how we're getting on with our directors, problems we might be experiencing on set. It's nice to know your friends are going through things just like you.

He's about to appear in the West End alongside Nicole Kidman. I remember when he made the decision. He'd been offered a big TV thing, but hadn't been on stage for a while, so I said it might be good for him. I can't wait to see it, and talk to him after. With some mates you have to be careful how honest you are when offering feedback. With Stephen, I can be entirely honest – and constructive, too.

He's a very relaxed guy, and he is taking to the ageing process so much better than me: I can't bear it, but he is so comfortable. He has his wife, his kid. He makes it all look so easy.

Stephen Campbell Moore, 37

Since making his big-screen debut in the 2003 British film 'Bright Young Things', Campbell Moore has appeared on stage, with the RSC and Royal National Theatre, and screen ('Wallis & Edward', 'Ashes to Ashes', 'Season of the Witch'). He is married to the actress Claire Foy, with whom he has a young child

The History Boys toured the world, on and off, from April 2004 until October 2006. We took it to London, Hong Kong, New Zealand, Australia and New York. In the middle of all that, we made the film version of it. By the time we got to Broadway, the production was winning Tonys all over the place – it was a sensation – but I think I had a slightly natural tendency not to get carried away with it all.

The whole tour was amazing. I remember me and Dom cycling to Bondi Beach, getting bikes in New York and cycling back to the East Village every night. Then, back in London, I ended up living at his house.

We had both been pretty busy for a long time up until that point; I know that I hadn't taken my foot off the pedal since leaving drama school in 1999. Perhaps that's why we didn't have a particularly productive time while we lived together. We effectively encouraged one another not to work, spending days cycling through London, looking for adventure, avoiding meetings, going for games of squash. It was a lot of fun, but I decided to move out after a few months as I really wasn't getting much done at all.

We've kept in touch ever since. I'll send out a text saying, "Coordinates?" And he'll text back, "Barbados, filming." Or else, "Tennis lessons." He's always taking tennis lessons somewhere, and he never seems to get any better. Which is good for me.

Back when we were living together and playing squash, we developed a couple of alter egos: Alan and David. Alan and David worked in high finance and shouted a lot, things like: "So, how's the Nasdaq, David?" We had decided that squash was basically an angry man's game from the 1980s, so we spoke in that way. Very silly, I know, but we were very good at wasting our time in such ways.

Once you settle down and have a family, you look back and wonder how you ever found so much time to waste. But then, that is where friendship is really forged, when you spend day in, day out with each other, having a laugh, arguing over silly stuff like the bills, or whether to cook a chicken with lemon and garlic.

Every time we see each other these days, we slip right back into Alan and David. There are people in your life whose company you just love, with whom you can talk nonsense.

But whenever I need him, he's there. I was ill four years ago, brain surgery. He was the first person to come around after, talking all sorts of nonsense, taking my mind off things. A lot of people wouldn't do that, but Dom did. That's what makes him such a true friend.

'Photograph 51', starring Stephen Campbell Moore, opens at the Noël Coward Theatre, London WC2, tomorrow. He can also be seen in 'The Go-Between' on BBC1 next Sunday