Born in Colchester, Essex, Rowntree was born to musical parents – Susan, a viola player, and John, a sound engineer at the British Broadcasting Corporation (BBC). He attended the Gilberd School, Colchester during the week, and the Landermere Music School, Thorpe-le-Soken, at weekends, where he studied percussion. He played percussion with his father in the Colchester Silver Band, a brass band.
