Hardy Railmotors Limited were a subsidiary of the Associated Equipment Co. Ltd and offered petrol and diesel engine shunting locomotives. C.F. Cleaver, an engineer employed by Hardy Railmotors, realised that the successful 130 bhp 6-cylinder AEC diesel engine used in London buses would be suitable for powering a lightweight railcar. The first railcar was a prototype, No. 1, and the body was based on the popular DB diesel unit called ‘Flying Hamburger’. After wind tunnel tests, the body was streamlined, which earned them the nickname ‘flying bananas’.
The railcar was bought by GWR and soon, No. 1 was displayed at the International Commercial Motor Transport Exhibition at Olympia in November 1933, to much fanfare and great publicity. GWR ordered more railcars and a total of 38 diesel railcars were constructed between 1933-1942. In service for various purposes, ranging from branch-line working to twin-set rail cars working the Birmingham to Cardiff service, these railcars were unique to the main line. Eventually, the railcars were withdrawn from service between 1955 and 1962. Three railcars are preserved: No. 4 at the National Railway Museum, No. 20 at the Kent & East Sussex Railway and No. 22 at the Didcot Railway Centre.