The massive increased in St Albans "desirability" started witht the Bed-pan electrification with the 317's starting (replacing the ramshackle DMU fleet , along with very well planned track configuration and resignalling from West Hampstead Signal Box , followed later by the introduction of the Thameslink operation.
In the early days of through working to the Southern, unit diagramming was done by South Central planning, at the request (IIRC) of those on the LM. Not completely straightforward as we had both 319/0 and 319/1 on the route, and as is often the case the timetable didn't allow for a natural 'balancing' of each sub class between Bedford,
Selhurst and Lovers Walk each night.
Here's something I took in last quarter of 1980. The Abbey station. The train was late arriving as I recall, the booked driver having phoned in sick, and so a Willesden man on his rest day had been woken up, and hastened to Watford Jn on his m/bike to work the turn.
BOLD - edited.