In message ,
Tom Anderson writes
How many sizes of tube train are there?
[...]
PS Sorry this has no relevance to oyster


Last week, taking a spell on the platforms away from Oyster stuff, I
saw a train which was much lower than anything else that runs on our
District/Hammersmith & City tracks.
I was told (thanks Ray B) that it was probably the Track Recording
Train.
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Kat Me, Ambivalent? Well, yes and no.