Windhoff Multi Purpose Vehicle (MPV)

The fleet of Multi Purpose Vehicles has, as the name suggests, a number of roles on the British railway network. A key role being rail cleaning and weed killing. The vehicles were bought by Railtrack to allow the withdrawal of a variety of ex-revenue earning vehicles performing these roles [1] and are based off Windhoff's Cargosprinter unit.
DR98904 RHTT duties through Huyton

Information
Number built: 32
Built: 1999-
Builder: Windhoff
Motor: 2 Railpac diesels
Power: 710 hp (530 kW)
Wheel arrangement: Bo-Bo

MPVs usually operate in pairs, one of the units being unpowered. Most of the vehicle (apart from the cab) is a flat bed - the engine, transmission and other machinery being under the floor in the manner of a DMU. This allows for equipment modules or pods to be installed as per the duty required, such as tanks for rail head cleaning (RHTT) duties.

Similar vehicles perform a variety of other duties on the network such as the double ended High Definition Switches & Crosses Video Inspection Train.
DR98909 on RHTT duties at Erdington

DR98958 at Leamington Spa

Another view of RHTT at Huyton

[1] Colin J Marsden, Rail Guide 2016 (Ian Allan, 2016) p. 218