I almost forgot..........."the TUBE" (subways)
Ah-hah, got ya there! Ya see, the "tube" is not synonymous with the "Underground".
How about that for a controversial statement from Ozzie??
The thing is, only some lines of the Underground are known as "the tube", namely the Bakerloo Line, Piccadilly Line and the Northern Line. The rolling stock used is quite different to that used on the other lines, District Line, Circle Line, Metropolitan Line,
because the tunnels used are much narrower and the trains just fit into the tube-like tunnels, whereeas the other lines have tunnels that are much wider and higher.
Ya see, old Ozzie's a well-travelled old gent!! Actually, I have more than a passing interest in railways. For example, my thesis at Uni for Economics was on railways.
Cheers, Ozzie