MIG wrote:
Why, when standing in a huge queue for a machine that turns out not to
work while the ticket office is closed, do I have to read notices
gleefully telling me how much I will have to pay if I get "caught"
without a ticket?

This is something you really want to write to the company about, and in
fact i'd urge you to. Ticket office open times have been cut a lot
lately, and this is said to be in reaction to the fact most people now
use Oyster, which can be topped up online, by phone, or of course the
machines or ticket office when available.

Unfortunately it doesn't work for everyone, as you've illustrated
above, so help us fight for better ticket office times by writing in!