* You do need to touch-in on Tramlink if you have a season ticket _if_
(and only if) you're travelling to Wimbledon, otherwise the automatic
gates that also serve the NR and Tube platforms get confused and will
charge you for a tube journey.

AFAIAA the situation is actually that the gates will refuse to let you out
at all and it is a deliberate anti-fraud measure. The reasoning being that
passengers could arrive on National Rail trains from far off destinations
without any ticket, or with the lowest price ticket that could have allowed
them to board the train at their origin station, and then have an Oyster
card with just a bus pass on it to allow them to exit. By forcing all
Tramlink users to touch in it means that bus passes will only open the gates
if the passenger arrived at the station on Tramlink.