BEING a screenwriter is all about trust.

You have to trust that actors will do your characters justice and when you hand your script to a director you have to trust that they share your vision.

But when Steven Knight wrote the screenplay for Locke he found he could not let it go so easily.

An innovative passion project on a small budget, he wanted to do the film his own way.

“It felt more like an obligation to be honest,” said Steven, who is best known for writing Dirty Pretty Things and Eastern Promises.

“When you write a film you see it in your head. You see it in a particular way because that is how you imagined it.

“I’ve been really lucky to then hand over the script to fantastic directors like Stephen Frears and David Cronenberg and incredible actors who have done such brilliant work.

“But it’s different to how you imagined it so in the end you feel obliged to try it yourself and take that film that is in your head and put it on a screen.”

Steven worked behind the camera for the first time on the crime film Hummingbird with Jason Statham and that got him thinking.

He told Weekend: “In the process of making that film we had done a lot of testing of digital cameras by shooting from moving vehicles “I found it hypnotic looking at that footage and I wondered if there were other ways of inviting an audience into a room, turning off the lights and having them engage with the screen for 90 minutes. Lots of things came to me at once. I wanted to do a film about the drama of an ordinary life and also a journey where someone begins with everything and they arrive at their destination and they have nothing.”

So Steven created the character Ivan Locke over Christmas and filming began just two months later.

TomHardy plays a man who has the perfect family and a top job in construction but a past mistake and his choice to drive from Birmingham to London could see his carefully crafted life fall apart.

Steven, who created BBC’s Peaky Blinders, added: “I wanted the character to be pretty much the most ordinary person and not one of those monsters and larger than life characters that Tom often plays.

“But that is as much of a challenge as anything else.

“Tom’s one of those actors that even if there are other actors on the screen people are looking at him. He just has that magnetic quality and this is something that for obvious reasons you need, someone who is very watchable but also someone who can pull off the performance.

“Tom loves things that are a challenge and that push the boundaries so he was on board with the idea.”

One of the most intriguing elements of the film is that it is all set in real time as Locke makes his motorway journey and takes and receives calls.

“I wanted to go back to a very basic way of shooting,” said Steven, who won a British Independent Film Award for Locke’s screenplay.

“We set up three cameras in the car and we had the other actors making the calls in a hotel conference room with a real phone line to the car.

“We had to deal with problems without stopping.

“For example, there was a rattle in the car. Normally you would pull over and sort that out but we carried on and it actually helped for a moment to add to the tension.

“If you invite the chaos of the world you can use it to your advantage. There is a police car that shoots past and there is a traffic jam at the perfect moment.

“The good thing about having the vehicle is that certain metaphorical issues are dealt with just by the reality of where you are.

“The future is down the road and the sat nav is telling you that is where you have to go. The past is in the rear viewmirror.

“So the structure was there already and I wanted the outside world to feel like chaos so we doubled up on the reflections and even trebled the reflections at times to make it feel like this uncontrollable movement of lights.”

Steven, who started his career writing and producing radio adverts, said that screenwriting will continue to be his ‘day job’.

He is currently working on the script for a sequel to WorldWar Z.

But he told Weekend that he wants to continue directing small budget performance-led films.

Steven added: “There are a lot of rules in film and scriptwriting which everyone will tell you can’t be broken.

“Studios will have their set way of doing things because it is a business and if something has worked before they will do it again.

But I also think it is time that some of those rules were challenged a bit.”

Locke is out now on DVD and Blu-ray.