Gull ID, Luxor, Egypt (1 Viewer)

This medium-sized gull was flying up the Nile near Crocodile Island, Luxor on 30 March. At first I though Black-headed Gull, but it seemed a little heavy. I'm thinking Grey-headed Gull, but I'd like another opinion. I'm assuming 1st winter, but in the process of moulting into summer plumage (tail). It's somewhat out of its normal range, but observer density is low so occurrence may be more regular than currently known. Anyone have any more knowledge than that?

Primary moult in March would be very odd for a northern hemisphere gull, does suggest it was born south of the equator . . . beyond that, not sure.

If it was moult but it's just broken feathers, the bird is a 1st summer black-headed gull. Structure and wing tip pattern lacking the all dark tip wrong for any other taxon.

Thanks Lou. Nice definitive answer there! My impression of ‘heaviness’ was very subjective, l know.