4 March 2017. 66431 is seen passing Wolverton dragging failed 68021 Tireless heading for Crewe Gresty Bridge. 68021 had worked from Norwich to Willesden the previous day and then continued on to Crewe on 4 March but encountered problems with coolant and overheating at Leighton Buzzard. 68021 eventually stumbled to Bletchley loop before being declared a failure. 66431 was scrambled from Crewe to collect the errant 68 for onward movement to Cheshire.