BR type 2 locos, 263 built by Brush between 1957 and 1962, Originally built with a Mirrlees engine, subsequently refitted with English Electric engines. Under the TOPS scheme the Mirrlees engined examples were class 30, the EE engined locos were class 31. Originally numbered D5500 to D5699 and D5800 to D5862. In the TOPS scheme the first 20 were numbered as 31001 to 31019 (exceptD5518 which had been rebuilt as a class 31/1 after accident damage). These locos had non standard controls and multiple working equipment. The standard locos were renumbered 31101 to 31327. Class 31/4 was class 31/1 locomotives converted to Electric Train Heating, numbered 31400 to 31469 Class 31/5 was class 31/4 with ETH isolated for engineering train use. The numbering retained the final two numbers, e.g. 31456 became 31556. Class 31/6 was class 31/1 locos through wired for ETH, but could not supply ETH. Class 31/9 was the former 31326 in Research Department use.