British Rail Class 507

The BR Class 507 was a fleet of thirty-three three-car 750 V DC electric multiple unit sets built at BREL York between 1978 and 1980, designed specifically for the Merseyrail Northern Line — the underground and surface suburban railway network serving Liverpool and its suburbs. The Class 507 was part of a major investment in Merseyrail infrastructure in the late 1970s that included the construction of the Merseyrail Loop and Link tunnels beneath central Liverpool, which transformed what had been a series of disconnected suburban lines into an integrated underground network on the model of London's suburban metro.

The Merseyrail network uses 750 V DC third-rail electrification, inherited from the Lancashire and Yorkshire Railway and Mersey Railway electrification schemes of the early twentieth century. The Class 507 was designed to operate on this system, with the three-car formation — shorter than the four-car units being deployed on the Southern Region and the WCML at the same period — reflecting the Merseyrail network's station platform lengths and the pattern of service on the Northern Line. Each set consisted of a Driving Motor Brake Standard, a Trailer Standard, and a Driving Motor Standard, with traction motors on both motor coaches giving good acceleration for the frequent stops on the underground sections.

The thirty-three sets entered service from 1978 as the Merseyrail Loop and Link infrastructure was completed, transforming services across the network. Under Merseyrail's distinctive yellow and grey livery — replacing the standard BR blue and grey — the Class 507s became the defining visual image of the Liverpool suburban rail network. The sets were maintained at Kirkdale depot and later Birkenhead North. A comprehensive refurbishment was carried out from the mid-1990s, updating the interiors and renewing the electrical equipment.

As of 2026, the majority of the Class 507 fleet remains in active Merseyrail service, now approaching fifty years old. The exceptional longevity of these sets reflects both the quality of the BREL York build and the scale of investment in refurbishment that Merseyrail has made over the decades. New Class 777 Stadler Metro trains are being introduced to replace the Class 507 and 508 fleets, and some 507s have been withdrawn as the new stock enters service, but a significant proportion continues to operate.