An odd combination at West Drayton on 22 June 1991 that proves the usefulness of the first generation DMUs. 55031 (L131) has been made into a three car set with the addition of a Class 101 DTCL and a Class 117 DMBS. It is pictured on the up fast line with the 12:10 Reading to Paddington Network SouthEast service. This train is an all stations service as far as Slough, from where it becomes non-stop to Paddington. Due to the closure of the relief lines just east of this point for engineering works, this Class 121/101/117 DMU lash up has been let out onto the main line to rattle its way to the capital at 70 mph in a gap between the HSTs!