Class 508

The 43 class 508 units were built in 1979/80 for use on suburban services from Waterloo. Passenger accommodation is all standard class, in saloons with double-leaf sliding doors. As-built, all carriages had 2+3 seating. Single leaf sliding doors give access to the guard's area and driving cab. Bodywork is of integral construction, with alloy skins on a steel frame and aluminium castings at the coach ends and around door openings. Units were originally formed of two driving motor coaches and two trailers. Each motor coach has four GEC G310 traction motors, rated at 111 hp, and camshaft control equipment. Rheostatic and Westcode brakes are fitted. Units have Tightlock couplers at their outer ends, with automatic brake pipe and electrical connections. There are emergency doors in the cab ends, but these are not available for passenger use in normal circumstances. Class 508 were the first production units for the Southern with air suspension, on BX1 bogies. Maximum speed is 75 mph.

When further suburban units were to be built a completely new design was adopted. Class 508 would have been a small, non-standard fleet if the units had remained on the Southern, so they were transferred to Birkenhead, to replace the LMS units on the Wirral lines. Three coach units were needed for the Wirral, so one trailer was removed from each unit and retained for further use on the Southern.

Subsequently, the number of units was found to exceed requirements at Birkenhead and twelve were transferred to Connex for use on local services in Kent, particularly Tonbridge to Redhill, the Medway Valley line and the Sheerness branch. Units were facelifted at Eastleigh before entering service in Kent in 1998-99. The original seats were retained, but reduced to 2+2 layout in the centre of the trailer coach. Seats were removed from the trailer and from one of the motor coaches to provide space for a wheelchair and bicycles respectively. All units are based at Gillingham and are in yellow and white Connex livery.

It is reported that the South Eastern units are to be further refurbished, so they can remain in service until 2011. This is likely to include provision of high-backed seats.