As a lad from the south I'd occasionally manage a day at Euston in the late 1970s but never took a record of which ALs worked which services to Birmingham, Manchester, Liverpool and Glasgow. Were they all interchangeable or did those based at Longsight for example tend to work Manchester services? Would an 82 be swapped in for an 86 or 87 with no particular concerns? Would an 85 run to Glasgow as often as an 81 etc etc?