The testing and commissioning of the units was mainly carried out on the WR, out of Paddington and Old Oak Common but I was not involved as I was still working for R&DD at the time.

210 001 was a four car version, and 210 002 was a three car. Each one had an above floor diesel engine of over 1000 BHP in one driving vehicle and were capable of 90mile/h. The principal behind the unit was to develop a diesel-powered train with the performance to match an EMU such as the class 317 hence the large engine required for fast acceleration.

The two sets were equipped with different power units, unit 210002 having the Paxman 6RP200L of 1,125hp in the Driving Motor Brake Second  with electrical equipment by Brush and 210001 had an MTU 12V396 TC11 unit of 1,140hp in the Driving Motor Second with electrical equipment by GEC.

210 001 comprised vehicles 60201 ,60401, 60400 and 60300

210 002 comprised vehicles 60200, 60450 and 60301

Although the performance was excellent, virtually a whole coach was sacrificed for the power unit and ultimately the option for a fleet was not taken up.

Unfortunately the units proved to be too expensive and wasteful of passenger space and the concept of marrying a high performance diesel train to an EMU was not pursued so they were eventually withdrawn in the late 1980's.The two driving trailers (and the intermediate trailer of the three car set together with one trailer from the four car set) were used in the Class 457 Networker development train. There was a plan for a driving motor also to be saved but, after the storage of the two of them at Eastleigh they were scrapped in 2003.

One of the TSO's is currently in class 455 set 455912 but the other two have been scrapped.