In a recent interview about his new book Skagboys, a prequel to the infamous Trainspotting, author Irvine Welsh briefly metions Filth and how he thinks it will be a truly iconic role for James:

So do you think the directors of the movies have captured the stories well?

Filth — and I’m not just saying this because I’ve had a lot of direct involvement — but I think Filth is going to be such an amazing film. I think [James] McAvoy in this is better than De Niro in Taxi Driver. He’s got all that kind of menace, but much more pathos and depth. It’s beautifully shot and it’s done in this Kubrick-esque symmetrical design and rich colour palette to play off his increasing madness. He just gets crazier and crazier. It’s very funny as well as very dark. If we get a nice iconic poster I think it’s going to be on every student’s wall, same as the Trainspotting one.