James was born in London, the second of two boys. His parents were from Trinidad, but he never knew his father. His mother, Phyllis Mary James, died when he was 12 and the boys went into a council children's home. An uncle living in the USA wanted them to live with him, but they didn't want to leave Britain. When he was 16 he was fostered with a social worker who had two older children, and they remain very close.
At 17 he began writing plays (Storm Damage was broadcast by the BBC in 2000 and won a Royal Television Society award in 2001) and he is also a highly-respected actor, with credits in Shakespeare, the films Elephant Juice, Lost in Space, Snatch, Lucky Break, 24 Hour Party People, Les Misérables and Among Giants, and TV shows Undercover Heart, Cold Feet, Out of the Blue, Comics, A Touch of Frost and Civvies, as well as a number of commercial voice-overs.