The Class 139 units are typical of the Parry People Movers concept, in that they utilise flywheel energy storage to recapture and supply the motive force for moving the vehicle.

[9] The concept of using the lightweight[3][6][7][8] railcar dates from 2006, when a year-long pilot scheme began on the Stourbridge Town branch line on Sundays, using a PPM50 unit constructed in 2002 and numbered as 999 900 under TOPS.

[11] Despite the difficulties in the commissioning of the two Class 139 units, London Midland consistently outlined its faith that they would be ready to enter service.

As a consequence, the vehicle, since purchased by Lightweight Community Transport,[16] underwent a major rebuild to bring it up to Class 139 standard, and was renumbered as 139 000, then later 139 012.

Parry People Movers used London Midland's operation of the Class 139 to promote the concept for other lines that are short and essentially separate from the main railway network as a means of reintroducing rail travel to areas that have seen it curtailed.

[20] PPM proposed a variation of the PPM60, to be known as PPM220, to bid for the contract to build a small fleet of experimental tram-trains for use on the Penistone Line,[citation needed] and for the new generation DMUs intended as part of the government's rolling stock plan.

[22] With Lightweight Community Transport, Parry People Movers developed concepts for a four–axle bogie vehicle with a more powerful diesel engine and greater passenger capacity, intending to market it as the flagship product for use on branch lines.