As well as a number of 2- and 4-car sets a couple of single railcars were also built for the Banbury (Merton Street) to Buckingham/Bletchley route. However being non-standard they were withdrawn (like the other Lightweights) after just a few years in service  by the end of the 1960s.
|Builder:||British Railways Derby Works|
|Engine:||2 BUT (AEC) horizontal 6-cylinder diesels|
|Power:||300 hp (224 kW)|
|Formation:||Driving Motor Brake Standard (DMBS)|
However some cars avoided scrapping and went into departmental service, one of the single cars became QXV RDB975010 Iris when it was transferred in 1967 to British Rail Research . Following rebuilding it was used for radio control and survey research at Derby  later it was used for radio propagation, noise measurement and data transmission tests . Now it has been preserved at the Ecclesbourne Valley Railway and has been restored to it's original condition.
|Iris at Duffield|
|Iris at Wirksworth|
 Brian Haresnape, Diesel Multiple Units: The First Generation (Ian Allan, 1985) p. 23
 Colin J Marsden, DMU and EMU Recogition Guide (Ian Allan, 2013) p. 28
 Colin J Marsden, Twenty Five Years of Railway Research (OPC, 1989) p. 96
 Haresnape p. 25
 Colin J Marsden, Departmental Stock (Ian Allan, 1984) p. 34