Most locos can be uncoupled and operated as a single unit or found parked and driven so why can't i uncoulpe a HST(GWR) loco and drive it as a single unit? Sorry i think i posted this in the wrong area.
All units and all carriages / wagons can be uncoupled in some form or another so I would imagine they just didn't think they didn't need to implement it given HSTs are normally in formed consists
They normally only get uncoupled for maintenance and repairs, never in service. So i think they just skipped that part.
