National Railway Museum’s National Collection Diesel D6535 returns to service following major restoration

Before and after: Diesel locomotive D6535 (Credit: GCR)

The Great Central Railway and 5305 Locomotive Trust are celebrating the completion of a major restoration project on the National Railway Museum’s National Collection locomotive D6535, preserving one of Britain’s most significant early diesel locomotives for future generations.

D6535 is an important part of Britain’s railway heritage and forms part of the National Collection. Built in 1960 by the Birmingham Railway Carriage and Wagon Company, it was one of a class of medium-powered diesel locomotives developed under British Railways’ landmark 1955 Modernisation Plan.

Ordered by the Southern Region, D6535 represented an enhanced version of locomotives previously supplied to the Eastern Region. Improvements included a more powerful Sulzer engine, electric train heating, and both air and vacuum braking systems. The Class 33 fleet ultimately comprised 98 locomotives across two variants, including 12 specially built for the restricted Hastings route.

The class became particularly well known for innovative push-pull operations on services between Bournemouth and Weymouth. Modified locomotives could haul trains in one direction before being remotely controlled from the driver’s cab of an electric multiple unit on the return journey. The system remained in service until the extension of electrification to Weymouth and was also employed on services to Salisbury and between Clapham Junction and Kensington Olympia.

D6535 entered service in December 1960 and was initially allocated to Hither Green before later serving at Eastleigh, Stewarts Lane and Old Oak Common. In 1993 it was named Hertfordshire Railtours at Weymouth Quay. Following withdrawal from service in 1998 after a shunting accident, the Railway Heritage Committee selected the locomotive for preservation within the National Collection.

After spending several years stored at Old Oak Common, where exposure to the elements led to significant deterioration, D6535 moved to the Great Central Railway in 2005 under the custodianship of the 5305 Locomotive Trust. While initial restoration efforts included partial rewiring, engine repairs and bodywork attention, extensive corrosion caused by prolonged outdoor storage required a far more comprehensive programme of restoration.

The latest project has included substantial structural repairs, replacement of heavily corroded metalwork, and extensive work to both driving cabs. Restoration teams also addressed long-standing issues caused by failed internal guttering and water-trapping body filler, which had contributed to widespread deterioration.

The completed restoration ensures that D6535 can continue to tell the story of Britain’s transition from steam to diesel traction and preserves an important chapter in the history of the Southern Region’s diesel fleet.