Yes; derivative Mark 3A/B loco hauled stock was later also built for the West Coast Main Line (plus a bunch of sleepers). I don't know whether the crash standa

Yes; derivative Mark 3A/B loco hauled stock was later also built for the West Coast Main Line (plus a bunch of sleepers). I don't know whether the crash standards for 125mph running were higher at the time. The Mark 3s are generally very strong, and have held up to high-speed crashes better than their predecessors, so something was definitely done right. They weren't fitted with central door locking until the early 90s, though, and even now it's not interlocked with either the train power or an 'actually closed' sensor - so it relies on the guard to make sure the train doesn't set off with a door open.