Has London ever had any bus routes whose outer terminal operates on the
basis of a "loop" say round a big housing scheme perhaps with some
journeys going clockwise and others anticlockwise round the loop?

Route 207A (not the Hayes-Chelsea one from the 1960s), withdrawn in
1999, went Uxbridge - Charville Lane Estate - Uxbridge in one
direction only, with a hail-and-ride section on some parts in the
Charville Lane area. The service was once an hour and the round trip
journey time could often match that, making the service horribly
unreliable.

The actual route was Uxbridge Road - (H&R)Hewens Road - (H&R)Pole
Hill Road - Charville Lane - Bury Avenue - Goshawk Gardens -
Weymouth Road - Kingshill Avenue - Lansbury Drive - Uxbridge Road.

http://maps.google.co.uk/maps?f=q&hl...0&ie=UTF8&om=1

The 207A was replaced by the (not so) half-hourly U7 route, diverting
off the Uxbridge Road past Hillingdon Hospital, which runs Charville
Lane Estate - Uxbridge as a normal route.