Walter Briscoe wrote:

Since then, I have been thinking about the teacup proposals, whose main
rationale seems to be that there is nowhere to store Circle line trains.
Aldgate seems a good candidate in both directions. Gloucester Road
clockwise and the line between High Street Kensington and Gloucester Road
anti-clockwise seem OK. (Does the latter allow passing Wimbledons?)
Hence my question above.

It's more than just storing trains - the Circle Line basically involves
trains running continuously for c20 hours, with no turn arounds and no
opportunity to recover time from delays. The latter has a knock-on effect on
the other three lines that share the tracks. (It's because of this that I
doubt there will ever be an "outer circle" *service* on London Overground.)
By introducing a couple of terminuses the individual train journeys shrink
to a far more managable length, they all turn around and it will be possible
to terminate a train early and reverse it in order to recover some of the
lost time table.

It seems to also offer an increased frequency on the Hammersmith branch as
well as on the Circle-only sections of track - I find myself avoiding
relying on Aldgate-Tower Hill services as much as possible (instead taking
wide detours to get the District elsewhere) because they have a reputation
as being just too unreliable.