'Ridley Scott is the most efficient director I've ever worked with,' says Leonardo DiCaprio, who stars in Scott's latest epic Body Of Lies.

'There are not many people able to focus simultaneously on six or seven different cameras at various angles and be a human editing machine. He's got seven monitors up there and he's able to flip from camera to camera and snap his fingers and say he wants to use that segment or that one or that one. He's able to accomplish huge sequences that normally take directors two or three days, in half a day. He knows exactly what he wants to put on screen.'

Indeed, even though there are more than 100 locations in the film and a host of breathtakingly complex action sequences, some shot with up to 15 cameras, Body Of Lies was, according to Scott, 'a doddle'.

'It was a pretty easy film to do, actually. You just know what you want and the more experience you have, the easier it gets. I have it all in my head beforehand, and I never shoot extra footage just in case. That's how you go way over budget. I learned not to do that on my 2,000th commercial before I did movies. Commercial-making was my film school. They taught me how to be very precise, to preconceive what you want and stick with the plan.'

Scott is so clear now about how to make these big-budget films that he has mapped out his schedule for the next few films. 'When I was first starting as a film-maker, I had done hundreds of commercials and was agonising about what kind of film to make. I couldn't make a choice. Now I know what I'll be shooting in four years' time and they're already being written.

'I know I'll be in England in January doing Nottingham and I'll probably be in Budapest next October doing a film of a book called Child 44 because it's already written. After that is (a Universal movie based on the Hasbro board game) Monopoly and then the Gucci family story. After all these years, I just know what I want to do. I haven't done a western yet. I have to do a western and that's on the side burner. It depends on how quickly you resolve the script because it's all in the writing. My most important ally in films is the writer.'