The English Electric D400's were introduced during 1967 and 1968 prior to full electrification of the London Midland Region to haul trains between Crewe and Glasgow. Built at the Vulcan Foundry Newton le Willows these 50 locomotives were unique in that they were leased to BR by the manufacturer.

With the introduction of the overhead electric system the class were gradually displaced and transfer to the Western Region followed as a replacement for the Diesel-Hydraulic classes. Reliability was a constant issue and availability often poor, this was finally overcome by the refurbishment of the entire class at BREL Doncaster between 1979 and 1983.

The withdrawal of the class began in 1987 and the final examples withdrawn from regular service in 1992. 50002 was one of the final 10 in traffic and was withdrawn in the summer of 1991 at Plymouth Laira. Shorn of nameplates, 50002 was displayed amongst the line of withdrawn locos at the Laira open day and purchased by the DDS shortly after.

Initially the locomotive was moved to the Paignton & Dartmouth Steam Railway and spent the next 6 years operating trains on this picturesque route. In 1998, 50002 left Devon on a five year hire contract that should have seen the locomotive overhauled and returned to mainline service, sadly this did not come to fruition. In 2003 after protracted legal action, a very forlorn looking locomotive was returned to the DDS and its new home on the South Devon Railway.

Once back in the care of the DDS a detailed inspection was undertaken and the findings were not good. Externally the locomotive had suffered from exposure to the elements with areas of considerable rot noted. Internally the power unit had seized, a result of the four exhaust ports being left uncovered allowing rainwater to run down in to the exhaust system pipework and then into the engine itself.

The DDS decided to return 50002 to as built condition and restoration of the locomotive will be undertaken in stages with the external restoration of the locomotive first. This would not only make the loco more presentable but ensure that it was watertight and allow the work of internal restoration to commence without risk of further deterioration of the locomotive. The majority of the electrical machines have already been fully overhauled and the focus will soon turn towards the power unit which the DDS intend to fully overhaul, to ensure that D402 has a long and successful future.

The D402 Appeal fund was launched to provide the funding required during the restoration of D402. No date has been set for the loco's return to operational condition for while the Society has both the skills and the enthusiasm, the work can only progress as resources (both financial and physical) allow.