Great Western Coffee Shop

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.

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. 

I don't know whether they were Revenue Protection or police / gendarmes (I think probably the latter) on a train we travelled in Paris, some 20 years ago.

There were three or four of them, striding very purposefully through the train. They were all at least 6 foot tall, with crew-cut hair styles. They may have been wearing pistols on their belts - but that's where my memory becomes a bit hazy: I think they were police, rather than RPI.

Whatever, you certainly wouldn't want to argue with them: the itinerant accordion player who had previously been annoying us within the carriage made an incredibly rapid exit from the train at the next station.  ;D

I don't think SNCF have RPIs as such: the contrôleur is both guard and RPI. I suspect any one-off raid would be done by extra contrôleurs. In their recruitment, SNCF complain that the public image of the contrôleur concentrates on the handing out of fines, ignoring the train safety and passenger assistance rôles.

But there is also the Securité Ferroviaire, which is SNCF's private police force. I imagine that hey would accompany contrôleurs if they needed protection or heavier enforcement. They are indeed armed, and (like anyone with a uniform and gun) they don't look exactly friendly - especially the big ones.
(https://www.groupe-sncf.com/medias-publics/styles/crop_1_1/public/2024-02/sugetransilien-guillaumeblanchon10052028-ban.jpg.webp?itok=vU7FMzZR)

They were in the news last week, having shot and killed someone at Gare d'Austerlitz. He'd been doing graffiti that included a swastika, and when challenged produced a gun (which was not real).

Thank you, stuving - that brings all of my memories back to me!  ;D

Years ago on the Tube, I saw a young man starting begging.The third person he approached produced an ID card that had sufficient authority to make the guy throw up his hands in acceptance and leave the train at its next stop.

I recall being on one of the trains in the Berlin area,

and two mean looking guys, one boarded at one end of the coach and one got in the other end of the coach

and then demanding to see passengers tickets after showing their I.D. 

They managed to find two who were not in possession of the correct tickets,

the two guys got the two passengers off the train and started interviewing them on the platform