The gateline staff didn't seem too interested.

I told gateline staff about someone I saw doubling up at KX suburban as he
was heading for KX tube, he did the same there in front of both of us. The
staffer just said they would catch him eventually during one of the regular
stings there. The impression I got is that the gateline staff are just
there to make sure no-one gets stuck and to let people through manual
barriers who are carrying luggage etc. They have no interest in revenue and
are probably not authorised to issue PF's and would not be in the game of
detaining someone who didn't have a ticket. In fact they would probably
open the gates if you asked nicely enough, lest they be acqused of "false
imprisonment" or kidnap?

D