Do you edit a comedy like All in Good Time differently to a drama or thriller?

There are additional pressures in comedy. There’s a different rhythm, but the thing about editing is – if you ain’t got it, you can’t edit it. It’s a bit like cooking; if you’ve got a bunch of shit ingredients it’s never going to be any good how ever well you cook it, and if you’ve gone out to get the finest ingredients, then pretty much whatever you do, you’re not going to ruin it.

So the scary thing is – you’ve got to get it on the day, and then you can play with it.

How do make sure you get it on the day, and how do you make sure you sustain an ensemble cast to keep on giving take after take?

I wish I knew. It starts with the casting – you need to put together a family of characters that gels and balances each other. Casting is like organising a dinner party – you have to worry about putting people next to each other in the right way. And then, although I hate this expression, you have to make sure everyone is on the same page. Everyone has to understand the script and be driving for the same result. That’s the point of rehearsals.

And then there’s this odd thing on the shoot which I can’t describe, but you’re just trying to make it real for the actors. You need to stage the shoot so it’s working for the actors and not against them. It’s about developing an atmosphere that suits. Sometimes you want people to feel happy and relax. Sometimes you want it to be quite tense.

Do you encourage your actors to improvise, and how do you do that? 

The word improvisation is a dangerous one and I try not to use it. You’ve often worked very hard on a script, or you’ve spent money on a very talented writer who has carefully honed it. The last thing you want to do is to have an actor trample over that and ruin it. What you talk about is adding. I started off in advertising, and they talk about adding value. What can we add to this scene that adds to it? How can we reinforce this moment?

You want happy accidents to happen, and you hope it will happen without anyone realising it. There’s that amount in On The Waterfront when Brando picks up and strokes the glove that Eva Marie Saint dropped by accident. He was smart enough to run with it. Entirely unscripted, a beautiful moment.

You’re from a generation of directors who are associated with shooting on location. Increasingly, more and more films seem to be studio shoots because of the capabilities that post-production provides. 

That’s because the world is too noisy now, so it’s an absolute nightmare shooting on location. You can barely get a good take without some unwanted noise happening. It can ruin a shoot. Studios are quiet and controlled. Digital post-production means you can replace anything with anything. It’s cheap and easy.

Is that a process you entirely welcome?

Yeah – fuck it. If it makes it easier, then whatever works. Doesn’t bother me. But in saying that, it would infuriate me to make a green screen film. I would hate to see my actors trying to act facing tennis balls with a screen behind them that can be turned into Troy crumbling. I like to go to a place and react to it, find it inspiring.

Do you wish you were starting out on your career now?

Hell yes. I had to wait 15 years after leaving university before I was able to make something dramatic. You’re not a director until you’ve directed something. And that’s a Catch-22, because no-one wants you to direct something until you’re a director. So how do you get around that?

When I was leaving university in the late 70s, to make a film on your own would cost the price of a house. Now it’s the price of a second-hand car. All you need is a second-hand HD digital camera and an iMac, and you can work to a professional standard.

The whole industry is about not being allowed in – when I started, even when you had made a film you would need to know your way around in order to get it distributed. It feels like we’re on the cusp of doing away with all of that, and that is very exciting.

 All in Good Time is in cinemas from May 11…