It was indeed 180110 today, but not the same vehicle that was involved in December. A hydraulic fluid leak is one possible cause (not fuel), which ignited when it came into contact with the engine. The fire detection system seemingly did its job, with the fire being extinguished quickly. What caused the bang remains to be seen when it is returned to depot, hopefully later this evening, but presumably it was the fire bottles going off as there was no structural damage to the engine visible. Part of the vinyls have blistered with the heat above one bogie.
As the train came to rest in a station platform, evacuation was made safely, quickly and efficiently by the on-board crew with passengers sent on their way by road a little while afterwards. Not a nice experience for those on board, obviously, but it was nowhere near on the scale of the December incident involving the same unit.
180110 was moved under its own power to Welwyn garden City, where is has undergone a thorough inspection by the fire service and maintenance staff from HT and GWR.
HT has all four units in regular service following the December incident and ice/snow damage during the early part of 2018, with no GC units on hire at present. Three are required for the daily service and with one on exam at the moment, cancellations will occur at least tomorrow.