In ups.com,
James typed:

And the turning needn't all be done before the loop is closed. It
seems perfectly possible to run trains (preferably in the late
evening) out of service Easling Common / Northfields - Hammersmith
(cross to the District) - Tower Hill - Aldgate - Edgware Rd -
Hammersmith (cross to the Picc) - Ealing Common / Northfields.

Oh yes. I wonder why they haven't thought of that. It seems much easier
than running them round the Heathrow loop.

*looks skywards*



Bob