Born in Duxhurst, Surrey, Simon is the youngest of six children born to Bob and Peggy Gallup.[citation needed] After moving to Horley, Surrey in 1961 he attended Horley Infants and Junior Schools between 1961 and 1971, followed by Horley Balcombe Road Comprehensive from 1971 to 1976. Between 1976 and 1978 he worked in a plastics factory and became the bass player for local punk band Lockjaw, who later evolved into The Magazine Spies (1979–1980), also known as The Mag/Spys.