Peter Kerslake says "Former G.W.R. Railcar number 4 had been the third of the batch of three introduced in 1934 and equipped with a mini buffet for use on express passenger duties between Cardiff and Birmingham , the popularity of such being that they were not large enough to cater for the increasing number of passengers .
With running gear and power units manufactured by A.E.C. of Southall mounted on frames built at Swindon the bodywork was from the Gloucester Railway Carriage and Wagon Company , although later units appear to have bodywork from Park Royal following some sort of collaboration between Swindon , Park Royal , the Gloucester Company and A.E.C.
This Railcar served her later years at Newport Pill Depot and was the oldest in service whilst there in 1956 , being restored by British Railways following withdrawal and is now part of the National Collection . "