• Number: D4, originally D8500
  • Class: BR Class 17
  • Designer: Clayton Equipment Co.
  • Builder: Clayton Equipment Co.
  • Built: September 1962
  • Configuration: Bo-Bo
  • Top Speed: 60 mph

Derek is a faulty diesel engine who works on Edward's Branch Line as a freight engine.



Derek is a jolly, enthusiastic diesel engine, who was brought in to assist Bill, Ben and BoCo at the China Clay Pits. Unfortunately, due to his engine, he is highly prone to teething troubles, namely overheating and suffering frequent breakdowns, for which he is apologetic for the inconvenience. As a result, he spends many a day having his engine tended to at the Dieselworks. But Derek is a likeable chap and even Bill and Ben decided that they liked him due to his friendly nature. Derek has an infectious charisma, is keen to help anyone around him, and has a passion for sorting things out in a jiffy - if his cooling system lets him.


Derek is painted in the BR Brunswick green livery with yellow warning panels. His window frames are lined, and the number "D4" is painted on his cab sides, in white. He originally had the BR logo on his sides.


North Western Railway
ThomasEdwardHenryGordonJamesPercyTobyDuckDonaldDouglasOliverEmilyArthurCharlieSamsonMurdochMollyRosieWhiffBillyStanleyHankFloraScruffPorterHarveyBarryConnorCaitlinNevilleBelleRyanFergusVictorMarionDustinDaisyBoCoBearDerek'ArryBertDieselBrushDiesel TenDenDartSidneyNormanPaxtonPhilipPipEmmaSaltyDennisStaffordFlynnWinstonSkiff.