700/1 - not sure now but - question not a statement - do TL drivers still have route knowledge via Lewes ? In FCC / 319s days there was a booked ECS turn that went that way exactly for route retention but I have a suspicion this nicety is not part of the current enterprise's way of doing things. I might be wrong.
700/1 can get turned but as all agree - rarely. In earlier 700s days a very small number of 700/1 DID work in services via Wimbledon loop during service disruption but to my knowledge has not happened recent years. Of course, if the same unit did that all the way to SAC and then all the back again it unravels itself, but I doubt any 700/1 would have lasted that long doing it (if only because FLU can not turn back at SAC unless it runs forward at least to Harpenden). Before anyone howls in protest about platform lengths, ASDO deals with that when a FLU stops at a RLU station RLU marker board. (Or at least it does when they call at Hendon, Cricklewood and Kentish Town all of which I have been on as a passenger.)
As posted upthread, there are numerous locations in south London where a 700/1 could theoretically get physically turned - but how many of those are left once you consider TL route knowledge ? These days if route A B C form a triangle, knowing A to B and A to C only does not permit B to C no matter how short it is, even one signal block.)