A Brush design and originally fitted with a Mirrlees 12 cylinder power unit, although all were re-engined with an English Electric unit by BR between 1965-69. The Class 31's went on to be the most successful of the type 2's and could be found all over the BR network in England working all types of trains, although primarily remembered for their secondary passenger work. The class survived in use until the end of BR and with EWS into 2000. A few remain in service with Cotswold Rail & Network Rail.