 On an unrecorded date he joined the illegal Ulster loyalist paramilitary organisation, the Ulster Volunteer Force (UVF); he was a member of the Portadown unit of the UVF Mid-Ulster Brigade.This brigade had been founded in 1972 by Billy Hanna, who appointed himself its first commander.Somerville was a close friend of senior UVF volunteer Robin Jackson, who assumed command of the Mid-Ulster Brigade upon the shooting death of Hanna.