They were ordered for London Overground, Chiltern Railways and London Midland (now West Midlands Railway)  The London Overground sets are likely to be cascaded elsewhere once electrification of the Gospel Oak-Barking Line they operate on is completed. Chiltern 172s cannot be fitted with tripcocks (a safety system used by London Underground) unlike their other DMUs because of the bogies used which means they cannot operate on the Aylesbury via Amersham Line unless running with another so-equipped DMU.
|Number built:||117 (39 2 or 3 car sets)|
|Engine:||MTU 6H1800R83 diesel per vehicle|
|Power:||968hp (720kW) / 1, 449hp (1, 080kW)|
|Formation:||Driving Motor Standard (DMS)+DMS or
DMS+Driving Motor Standard Lavatory (DMSL) or
DMSL+Motor Standard (MS)+DMS
It is in service with London Overground (Class 172/0), Chiltern Railways (Class 172/1) and West Midlands Railways (Class 172/2 and 172/3). The London Midland examples have end-gangways in the Electrostar style. The 172/3 are 3-car sets with the other sub-classes being 2-car.
|Chiltern 172 104 at Princes Risborough|
|London Midland (as it was then) 172 331 at Worcester Shrub Hill|
|West Midlands Railway 172 339 at Birmingham Snow Hill|
|LM 172 335 and 332 at Birmingham Moor Street|
|London Overground 172 008 at Gospel Oak|
|WMR 172 335 at Dorridge|
 Colin J Marsden, DMU and EMU Recognition Guide (Ian Allan, 2013) p. 162