first time I have seen RPI's actually on the tube trains

[whole diary]

[infoman]

three of them from Latimer Road to Ladbrooke Grove,late saturday afternoon saturday 11 november 2023.

Don't think it was connected with Armistice Day as it was a little bit too far away from the Protest area.

[johnneyw]

Can't remember seeing any on the London underground but recall seeing them fairly regularly on some of my visits to Hamburg.  The method was for a fair number of the HHV revenue protection staff to board a carriage "incognito" and only when the U or S Bahn moved out of the station would they produce their I.Ds and check people's tickets/passes.  They fairly frequently caught someone who hadn't paid and they had the security of numbers to carry out their work without the culprits thinking that they could make a getaway or resort to intimidation.  You really couldn't tell them from the other passengers especially as they appeared to be a very representative mix of what you'd expect to see on the train.
My brother and myself once realised we'd travelled a couple of stops beyond our day card zone and had seen enough people caught out that day to be more than a little relieved when we were back in safe territory again.