Complex sentence: Sewell was educated at Orleans Park School, a state comprehensive school in Twickenham, which he left in 1984, followed by West Thames College, where a drama teacher spotted his promise and sent him to audition for drama school.
Split into simpler sentences: Sewell was educated at Orleans Park School, a state comprehensive school in Twickenham, which he left in 1984. On leaving school he attended West Thames College, where a drama teacher spotted his promise and sent him to audition for drama school.