Constructed in Birmingham, the Class 101 DMU was one of the longest lasting DMUs to ever see service in the UK. 527 of the class would be built across many orders from BR between 1956 and 1960. The first units would enter BR service in 1956 in the BR green livery.

Class 101 units at the height of their use could be seen in all corners of the UK, at the onset of privatisation in the 1990s the units would appear in all manner of colourful liveries such as the Network South East colours and First North Western. Throughout their life, Class 101 units would occasionally appear as a three car sets where demand dictated.

Beginning life as the BR Class 101 unit 50338 On its entry into departmental service the unit would be reclassified as a class 960 and renumbered 901002, it would also gain the name Iris 2 which would be displayed in place of a destination on its destination boards.

Iris 2 functioned as a lab for Network Rail undertaking tests around the UK. As Iris 2, the DMU appeared in a Serco Railtrack livery, Network Rail livery and a unique grey Lab 19 livery. Iris 2 is currently preserved on the Barry Tourist Railway in a BR Green livery.