In message , Brimstone
writes

Are they running a special timetable prior to the closure in order
to get all the trains the same way around during the closure, or is
there no such thing as a 1973 stock being "the wrong way around"?

Unfortunately, there is. When the stock was built, there was no such
thing as the T4 loop, and all the stock was built handed.

Only the double ended cabs are handed.

Single ended units come in A and D end variants (Even numbered ones are
A end and odd numbered ones are D). Double ended units have an A and a
D end cab.

A unit is three cars, hence two together make a train.
--
Steve Fitzgerald has now left the building.
You will find him in London's Docklands, E16, UK
(please use the reply to address for email)