Pressed Steel built single car DMUs. These single car trains are ideal for diesel-era branch line passenger services on small layouts, being a completely self-contained train with the future option of coupling additional cars or trailers for 'peak hours' trains. The Pressed Steel class 121 cars have had long lives, being built in 1960 and while most were withdrawn in the mid-1980s several were retained for shuttle services, the last being withdrawn from Network Rail registration in 2017. Of 16 cars built only 3 have been scrapped leaving 13 cars, from which several are in regular service on heritage railways.
Production due to start after the 122s in late October, with delivery probably Spring 2021.