District Line and S stock

I had my first experience of the new and long overdue dot-matrix train describer at Barking station, platform 6, last Sunday. The trains (or more correctly, services) were all described as 'District Line'. I thought, Ok, maybe it's not a good idea to describe them as Ealing Broadway, Richmond or Wimbledon as the correct thing to do is to get the first train and change where appropriate (typically Earl's Court). However, the first train along was a C stock train bound for Hammersmith via Edgware Road.

Admittedly such trains do run on the District Line Wimbledon / Edgware Road Branch, but this was clearly a Hammersmith & City Line Train.

When the new S stock trains entirely take over, the platform and train descriptions will become more important as the type of train stock will not give a clue to its route. The trains on the Metropolitan line will be 8 coaches  long, and those on the District, Circle and H&C will be 7 coaches long. As things currently stand the Met doesn't come to Barking, so even that hard to spot difference won't help.

I say as things currently stand, because there is talk of returning the Met to Barking and running the Ham & City out of Aldgate. This is all rather academic, because all these lines are joined together and all the trains can run any route, in theory. When the trains are all S stock they can run Upminster to Uxbridge if they want.  As they run on largely the same tracks they use largely the same platforms, so changing is dead easy. All they must avoid is service patterns that confuse the customer.