Personally, I wouldn't rule out that they may be training chips as usually only cash jetons were used on FR (according to many people I've spoken to, and not just Playboy staff). As to the possibility of them being training chips, the main reason I say that is that they (presumably) trained French roulette dealers and may not have wanted FR cash chips to be used (I wouldn't have thought) so maybe they used them for that reason. According to the ex-Training officer, the AR chips roughly corresponded to the cash ones in colour which may be relevant as the jetons don't from what I can tell which may mean they weren't but I still wouldn't discount it.
Maybe they had the idea of combining the AR style of having your own colour on a FR table, possibly due to cash chips causing too much of a problem and it's much easier to deal that way (less disputes), obviously. If so, it doesn't look like it "took off" or I'd expect to have seen others appear over the years.
Maybe they didn't put values on them as it may have been the time when the UK currency was being decimalised and they'd already had to make new cash chips and they were trying to save money.
As the London FR table closed in the early 1970s, I doubt they would have still been in use by the time Playboy closed so they probably were in use for longer than a few days (but anything is possible) unless they weren't FR jetons.
The main reason Playboy lost their licences was because Hugh decided to appoint American management, obviously all the dodgy dealings were the catalyst (but there were lots of casinos doing the same type of thing) but , which really didn't help with the Gaming Board. I believe Victor had quite a bit to say about that in one of his books.