R40554 Railroad Mk3 TGS Trailer Guard Standard GWR 44086British Rail introduced the production version of the Mk3 coach in 1975 with improved standards of comfort in response to competition from airlines and increased use of private motor cars. Designed and built by BREL, initially they were intended as locomotive hauled stock, but with the development of the High Speed Train (HST), were soon adapted for use at speeds of up to 125mph (220km h). The first version of the Mk3 coach had actually been built in