I assume they are just generic raccoon dogs, most likely from a private collection as most raccoon dogs in UK zoos have come from private keepers.
To my knowledge, all have!
The complicating factor is that there has been at least one import of pure Japanese into the private trade in the past year or so, according to my sources; as such, when one considers how common the taxon is becoming in private collections, and the scope for people to take on animals they cannot cope with, I would not be surprised if Japanese start popping up in rescue centres and small zoos as time goes by. At least one individual already has.
However, I suspect you are certainly correct that the raccoon dogs mentioned earlier *are* generic.