"Ernesto" wrote

I traveled on the WLL later on in the day, the line diagrams on the 378 I
rode on made no mention of the ELL at all, not even as "under
construction".

There are two separate fleets, one (DC only) for the ELL, and another (dual
voltage) for the NLL/WLL/Euston-Watford DC. It makes sense only to include
line diagrams for the lines the trains will run on. Similarly D stock don't
include the Circle/H&C on their line diagrams, and C stock include
Wimbledon - Edgware Road, but not teh rest of the District.

Peter