The Conversation: Actor Daniel Mays on financial struggles, being a workaholic and taking on a new project at the Donmar

"My agent says, "Turn stuff down". But I always think someone's going to tap me on the shoulder and say, "Your time's up"

Mays says: 'It is tough to do two plays at the Donmar in one year - it's financially tough, I'll be honest with you.' (Frantzesco Kangaris)

You're in a new play at the Donmar, The Same Deep Water As Me. What's it about?

It's set in Luton in an injury claim law firm. My character, Andrew, has tried to be a big-shot lawyer in London but things haven't worked out and his dad is dying. He gets told about 'crash for cash' – doctoring car accidents for insurance claims – so he gets involved in that. It's about stepping over the mark into criminality – it's also about lying.

Have you used a personal injury lawyer?

I haven't, no, but it's all come from Nick [Payne, the playwright]. The artistic director's brother is a defence lawyer for a big company and has to defend against claimants, and Nick was invited to a court case. He was blown away by how shit people were at lying and would just push to get as much money as possible. We're living in desperate times when people will go to extreme lengths for survival.

You're going to be in Common, a new film by Jimmy McGovern. How's that shaping up?

It's Jimmy's new piece about the joint enterprise law. If you're involved in a gang or if you are connected to a murder like a stabbing, if everyone says "No comment" you can sweep that whole group of youngsters up and try them on joint enterprise. It was a law that was introduced to stop aristocrats duelling –now it's being used on the council estates.

You've done film, theatre and TV – which do you prefer?

Theatre, because you are entrusted to take on a character and play him over an evening. There's a lot of hanging around on film and TV [sets], but if directors create a theatre-like atmosphere, like Mike Leigh does, you feel like you're in an ensemble.

Is there a danger with big films, in that you don't know how it's going to turn out?

Completely. You feel like a cog, you're not told what's going on. But Atonement was a massive movie, and yet Joe Wright made me feel integral to the story. Some directors don't do that…

…Michael Bay?

Yeah, you can think 'Why am I here?'. But a good director will always make you feel wanted.

How do you relax?

I've been running since January and that clears my head, but I'm a workaholic. My agent says, "Turn stuff down". But I always think someone's going to tap me on the shoulder and say, "Your time's up".

But you've never been out of work.

Sometimes it is good to take stock and just see what you've done. But the problem is I can see the benefit of every project. John Crowley's directing this play, and his track record speaks for itself, and the Donmar has such great integrity.

You feel you can't turn them down?

I can't. I mean, it is tough to do two plays at the Donmar in one year – it's financially tough, I'll be honest with you.

So TV is more lucrative?

Without a doubt. Subsidised theatre is tough on your pocket which is why you won't get many film and TV actors doing it. But actors should participate, because you never know what's going to come of something. You have to be in the game and see what happens. Because it is a game… it's all a load of old shit [laughs].

'The Same Deep Water As Me' is at the Donmar Warehouse, London WC2, 1 August to 28 September

Biography

Daniel Mays, 35, is an actor from Essex. He got his big break playing a thuggish boyfriend in Mike Leigh's All or Nothing, and went on to appear in Vera Drake and Made in Dagenham