The 1922 grouping of the TVR into the GWR gave the rail network of South Wales greater access to the design expertise at the Swindon railway works. In 1926 a new coal truck was proposed which increased capacity to 21 tons but which could also be used for transportation of other minerals such as ballast for the permanent ways and iron ore for the steel works etc. These wagons required maintenance and the Taff Wagon Works would have undertaken sub-contract work on behalf of the GWR. [082]