In view of suggestion noted on one of my earlier postings that this might be a hybrid, I am submitting a few more shots in case they help clarify. Fairly extensive investigation convinced me that its features all accurately fit Carduelis sinica which, incidentally, I have seen in the wild in Japan. This shot shows the characteristic yellowish-green rump. Only the origin remains suspect. Does anyone know of this species in captivity in Europe, apart from one in the Tierpark Zoo, Berlin in 2008 (with web reference if possible)? Incidentally a pattern seems to be emerging of the few European sightings all being in spring.