Western Reef Egrets turn up in Europe only as rare vagrants - their main distribution is around tropical and subtropical coasts of Africa and parts of the Middle East. There are two colour morphs, the dark slaty one shown and a white one which looks very similar to Little Egret, but Western Reef Egrets have a longer, slimmer bill which is often more extensively yellow than Little Egret's, and the yellow of their feet can extend up the legs (I've not really selected the best photo to illustrate these differences!) They are coast-dwellers, preferring shores, estuaries, mudflats, lagoons and mangroves.
It'd been a while since I attempted a bird in flight, I'm rarely pleased with the results and this time was no exception! That shade of yellow is way too lurid for the feet too, looks like I've used a highlighter pen - argh!