I don't have it to hand, but there's a photo of an MV class with ballast wagons at the end of Barry Carse's book on the Irish Metro-Vicks, and he states that they're ex-SNCF stock.
The older ballast wagons were ex-BR seacows.
Robert, unfortunately those Mistral wagons are out of production and it doesn't look like there'll be a re-run anytime soon. I've been trying in vain to find some for an absolute age!