 The prototype class 252 (power cars 43000 and 43001) took the world record for diesel traction, achieving 143.2 mph (230 km/h) on 12 June 1973 on the East Coast Main Line between Northallerton and Thirsk.On 1 November 1987 the record was raised to 148.4 mph (238 km/h) by a shortened class 254 set running speed trials between Darlington and York.On 27 September 1985 a shortened class 254 set carrying passengers ran non-stop from Newcastle to London King's Cross, averaging 115.4 mph.