The FFI do seem to have had Cromwells and a handful of Cavaliers.
Not something I know much about as decent books in English on French Armour seem to be all but non-existent.
I'm very interested though as this is not unlike my longstanding quest for more info on postwar French Panthers, something's also nagging at the back of my mind that some of the Centaurs & Cromwells used by Greece postwar may have come via France?? Really not sure without a bit more checking though

.
As Ross's query is so old I guess he might have found more by now.
Cheers,
Adam.