Fletcher trained at the Anna Scher Theatre. His first film part was as Baby Face in "Bugsy Malone" (1976). He made his stage début the following year in a production of "A Midsummer Night's Dream". As a youth actor he was regularly featured in British productions in the early 1980s, including "The Long Good Friday", "The Elephant Man" and "The Bounty". In 1987 Fletcher was cast in Lionheart. As an adult he appeared on television as the rebellious teenager Spike Thomson in "Press Gang" and in "Murder Most Horrid" (1991) with Dawn French. He has also starred in the films "Caravaggio" (1986), "The Rachel Papers" (1989), "Lock, Stock and Two Smoking Barrels" (1998), "Layer Cake" (2004), AffirmFilm's "Solomon" as Rehoboam and Universal's "Doom".