The master faker of pictures preparing for Mike Leigh's film about JMW Turner

Mike Leigh is the latest director to require artist Charlie Cobb's services, for his new film about the great British artist JMW Turner, currently shooting in the UK. Cobb has churned out many fake Turner paintings for the still untitled film, due out in 2014, in which Timothy Spall plays Turner.

Some of his fake Turner paintings are so big they're sticking out of the tarpaulin roof of his studio, although he assures me they're fine because with oil paint it doesn't matter if they get wet. But what does matter to him is doing research and using the right materials to recreate the look of the famous artist's paintings.

“Quite a lot of the historical pigments were toxic, like chrome yellow, and have therefore been phased out. Instead I had to buy the pigments in powder form and grind them in oil, just as the likes of Rembrandt would have done,” explains Cobb. “Then to age the paintings, I had to put a yellow glaze over them, and mix the paint with grime to make them appear dirty.”

Cobb is probably not a name you've heard of, but you will almost certainly have seen the artist's work in many films. Entrenched in a refugee-camp-style studio in his back garden, he has produced art and craft work for a wide variety of films from Star Wars and Trance to The Queen. He is always on standby – often having to produce artworks super-fast.

Leigh is renowned for working off the cuff, getting his actors to improvise, which keeps the cast on their toes, but proves especially challenging for the production team.

“In the spirit of this spontaneity, I produced several Turner paintings in a short space of time, which was actually how Turner worked, quickly wet-on-wet,” says Cobb. He was required to do a similar process for Danny Boyle's art heist film Trance, in which the Goya painting Flying Witches is stolen. “I actually went to the Prado Museum in Madrid to see the painting and understand how Goya built up the layers of paint.” For one scene in Trance where James McAvoy's character dreams about a room full of famous stolen paintings, he visited the office of the Art Loss Register in Hatton Garden where he was provided with reproductions of the stolen paintings.

Cobb's extensive portfolio also includes creating model Star Wars spaceships out of foam board for Revenge of the Sith; painting Helen Mirren's regal portrait for The Queen, which is finished off by actor Earl Cameron in the film, and creating the painting that Bill Nighy saves in Richard Curtis's The Boat That Rocked.