At Bough Beech Resr, Kent this afternoon we found a small Egret which had bright yellow lores although the yellow didn't extend to above the bill as I believe it should in Snowy. It had loose feathering on the breast but there were no filo-plumes on the nape which the 3 Little Egret in the area all displayed. There appeared to be some yellow-green up the lower half of the rear of the tarsus and the feet didn't appear to be the bright lemon yellow of Little, the tibia looked all dark. The base of the lower mandible was a salmon pink colour. The iris appeared dark with a yellow eye-ring. In flight the bird appeared c10% smaller than an accompanying Little Egret, unfortunately when they landed the Little landed behind a tree stump and I coudn't tell if it was perched on part of the stump as it appeared huge compared to the subject bird which was c10 feet away.
I've appended 4 rather poor images taken with the camera-phone as this was all I had with me, but at least it gives you some idea of the jizz which I believe is more Little than Snowy.
In BB Vol 98 213 there is a letter (with a photograph) describing a Little Egret with yellow lores so it's not unheard of.
All the best,