Paul Corfield wrote:

The first two were rumoured to go into service about 10 days ago. They
didn't. There are all sorts of comments flying around as to why they
didn't but it seems like paperwork is the issue. There are apparently
several units ready to start service having accumulated sufficient fault
free running. As others have said more units are at Willesden awaiting
preparation and enough trained drivers while even more are stacked up at
Derby.

The 378s under delivery now are dual voltage for overhead and third rail
current collection. The fleet for the East London Line are DC only.

I see. But is it safe to say there's really no difference between the
378s that will run on the East London Line and those that will run on
the North London line, save for the fact that one part of the fleet will
have a pantographs mounted on their roofs?