"Zobo Kolonie" typed

Yesterday at Victoria underground station I heard an announcement reminding
"customers" with Oyster cards to always touch their card to the pad on their
way out of a station. What does that mean? Does it mean that if the gates
are open (e.g. when there's nobody around to staff them) then prepay
passengers can get away with a free ride?

They could, if the gates were open when they entered the Tube and when
they left it. Otherwise, they get an 'unresolved journey' which can be
charged at rather more than the fare for the journey taken.

--
Helen D. Vecht:
Edgware.