James McAvoy came close to missing out on his highly-acclaimed role in Filth due to his clean-cut looks.

The X-Men star has received rave reviews for his turn as corrupt, cocaine-snorting cop Bruce Robertson in the big screen adaptation of Irvine Welsh's stomach-churning novel.

But director Jon S. Baird admits he was unsure how the clean-cut Scot would bring the role to life, until he met up with MCAvoy, who showed he had a deep understanding of the bipolar character's mental health issues.

The filmmaker tells the Bbc, "He looked very young this particular day. But 20 minutes after talking to him, he had morphed into this middle-aged, grizzled, alcoholic divorcee. It was pretty mad.

"He started talking about his experience with mental illness, and that's the thing that bonded us. He had experience of that with somebody he grew up with.

"As soon as I knew he understood that, it was game over. It was like, 'He is the guy'. We offered him the part the same day."