Vehicle 55020
Type: Pressed Steel Class 121 DMBS (Driving Motor Brake Second) "Bubble Car"
Owner: Chiltern Railways
Home Railway: Aylesbury - Princess Risborough Branch
In BR passenger service: 9/1960 – present

The Western Region ordered more Bubble cars following the success of the 1958 GRCW cars.

At one time 55020 was converted to Sandite / Route Learning car 977722.

In 2003 the vehicle was selected to undergo extensive refurbishment for a return to passenger traffic. It remains as the last first generation DMU in passenger use on the network.

55020 be in traffic at Railcar50.