Sturnus roseus

Unfortunately midway between winter and spring and the picture is of the rear view only, but from what has been said, I would think David is right it seems a young bird.

Lars Svensson ID Guide to European passerines does not appear to use bill colour as an age/sex criteria. Both ads and juvs have complete moult by winter (he says most in Oct/Nov).

Adult male in autumn - all wing feathers and coverts blackish with strong blue-green gloss. When in active moult, unmoulted WF are about as dark as new and lack the pale edges of juv feathers. In spring plumage, much as autumn but pink of back and rump revealed through wear - generally no brown tips left by March.

Ad female blackish-brown WF and wing C with some gloss. Ad fem. spring much as autumn but pink of belly revealed. Pink of upper-parts shows partially esp on rump, but at least some brownish tips present on mantle through May.

1Y male wing feathers edged pale. After completion of moult become very difficult to separate from ad female, but keep odd juv secondaries or juv alula covert through winter.

Separated from 1Y female by presence of pure pink basally on belly (a tricky thing to see I guess if not in the hand!).

2Y male very similar to ad female. Centre of throat often with some off-white feather bases visible (I guess also seen by blowing them!).

2Y fem. like 2Y male though duller and virtually without any pure pink at all. Hind-neck dull brown-grey, not blackish or black with gloss.

Seems to be most likely a young bird but for some features clearly need to be seen at very close range. You'll have to catch it Richard I guess!