66733 Cambridge PSB has had an interesting numbering system, having initially been numbered as 66401 at import, when the locomotive joined the DRS fleet. One of five Class 66 locomotives sold to GBRf, the locomotive was renumbered as 66733 on March 2, 2011 but due to GBRf being short of traction it was put back into traffic before the number could be physically applied and retained 66401 as its number, this being rectified on 10 April 2011. On 10 September 2014 the locomotive was named Cambridge PSB by GBRf Managing Director John Smith to celebrate over 30 years of Cambridge Power Signal Box serving the Fen Line and Cross Country routes.