"Brian Watson" wrote

This got me thinking literally, "are there any depots or
strategically-placed triangular junctions at which a train could be turned
right round?"

LU trains are not, as far as I know, biased to be driven from one end or
the
other, but I could see circumstances such as the Circle Line where it
could
be an advantage to turn a train to even out wear on the wheels.

The surface lines have triangular junctions at Earls Court and Aldgate, as
well as Moor Park/ Rickmansworth/Croxley. The Northern Line has a reversing
loop at Kennington. Piccadilly Line reverse by running around the loop at
Heathrow. Central Line can turn by running right round the Hainault Loop.

Peter