High Quality Content by WIKIPEDIA articles! British Rail Class 507 electric multiple units were built by BREL at York works in two batches from 1978 to 1980. The first thirty sets were constructed from September 1978 to mid-1979 and a further three were added during 1980. They were the second variety of British Rail`s then-standard 1972 design for suburban EMUs, which eventually encompassed 755 vehicles and five Classes (Class 313/314/315/507/508). The 507s were the first variant to be 750V DC third rail only. They have worked on the Merseyrail network from new, and continue to do so, now refurbished by Alstom`s Eastleigh Works.