 On its creation in 1918 the constituency consisted of the urban districts of Bedwas and Machen, Bedwellty, Mynyddislwyn and Risca and the civil parish of Rogerstone in St Mellons Rural District.These areas had previously been divided between the West Monmouthshire and South Monmouthshire constituencies.The House of Commons (Redistribution of Seats) Act 1949 removed Rogerstone into the constituency of Monmouth from 1950.