I never thought I would see a Class 166 working a train from South Wales along the Great Western Mainline, but the total timetable meltdown caused by the discovery of underframe cracks in the Class 800 & 802 fleets resulted in some desperate substitutions. Most trains were cancelled, but here we see 166215 passing South Marston on 12 May 2021 with the 1L07 07:26 Newport to Reading GWR service, surprisingly only running a few minutes late. The humble Class 166 has been around for nearly three decades, and apart from one or two minor issues, has been totally reliable. Perhaps the engineers who worked at BREL should explain to those at Hitachi how to make a welded aluminium train!