Charles Ellson ) gurgled happily, sounding
much like they were saying :

sigh
Tube in the sense of "London Underground", rather than tube in the
sense of the actual engineering behind the line itself.

"Tube" in the sense of a buzz-word slavishly copied without
bothering to recognise the correct meaning ?

Yes, that'll be it.

Otherwise known as "in the sense that several million Londoners use it
every day, rather than the sense that a handful of railway anoraks
insist on it being used when they're feeling *really* pedantic and
trying to score points..."

So the proper usage by hundreds of staff (to whom the system actually
"belongs") doesn't count ? Many Londoners also mis-name St.Stephen's
Tower (and others slavishly follow) but that doesn't mean their usage
is correct.

If you want to be really pedantic about it, the outer reaches of the Met
are neither London nor Underground...