In message , at 01:03:21 on Fri, 26 Feb
2016, Basil Jet remarked:

So outside Stratford there would be three roundels - "Underground",
"Overground" and "Elizabeth line". That would be weird - it instantly
puts the question "Why doesn't the Underground roundel say Central
line" in your head.

You forgot the Jubilee Line, DLR and Abellio GA.

What roundels are outside Wimbledon, which has Underground*, Tramlink,
and National Rail (genuine question).

* Rather than District Line.
--
Roland Perry