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.
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.
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).