In message .com, Paul
Thompson writes

Please could someone suggest the best/most definitive book on the
underground? I'm totally new to the subject, and wanted to start with a
book that won't waste my time.

Since so much has been published on the subject, you are likely to get a
number of diverse suggestions.

For me, the most comprehensive and authoritative historical study is:

Desmond F Croome and Alan A Jackson, Rails through the clay: A
history of London's Tube railways, Capital Transport, 1993.

Be aware, though, that (a) it deals only with the tube system and not
with sub-surface systems such as the District and Met, and (b) it is
currently out of print. Second-hand copies are often *very* expensive,
but it is at least worth getting a copy through your local public
library.
--
Paul Terry