"77002" wrote

In the late seventys I was privalidged to have an extended visit to
Neasden Depot. I remember some discussion about 3 car and four car
sets. I wonder if this may have related to Bakerloo Line stock.

You are probably correct about the Bakerloo being 4+3, though I don't think
any LT trains in Central London (apart from the Aldwych branch) have run at
anything other than full length since WW2.

Short trains of tube stock have run since WW2:
Epping - Ongar (3-car)
Hainault to Woodford when it was a self-contained shuttle
Holborn - Aldwych
East London Line, during the period after ancient District stock was used
until A stock took over.
Acton Town - South Acton was worked by single car units of sub-surface
stock.

Peter