Class 23

Ten pilot scheme English Electric Type 2 diesel-electric locomotives. The class suffered major problems throughout their short lives and were destined for early withdrawal, the last D9509, leaving traffic in March 1971. One machine, D5901, went on after withdrawal to power research trains based at the Railway Technical Centre, Derby.

Engine: Napier 9cyl "Deltic" T9-29 two-stroke, pressure charged, of 1100bhp at 1600rpm.

Numbers: D5900-D5909 (no TOPS numbers carried).