"John Rowland" wrote in message
...
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.

Fortunately the Aldwych branch still existed at the time, leading to a
quantity of double-cab units being built.