Hi Dave, I guess the critical distinguishing feature for me, on the pics at least, is the different bill pattern on the two birds. The top left pic in Lyndon's set clearly shows a bright orange-yellow basal half to the bill, the bird at Hubberton does not have any orange-yellow on the basal half of the bill, it is pale grey.
The more subtle plumage colours tend to get burnt out on photographs of white birds, particularly when the photos are taken in bright sunlight (which, at this time of year, is almost essential if you are going to get a half-decent photo), so perhaps we have to rely on structural differences (and behaviour) to separate individuals. That being said, the plumage details on the Angle bird are there for all to see in the field - they are just not always obvious on pics taken in direct sunlight.
For info, I believe that the bird I saw fly in from the beach at West Angle was a different individual to the bird I later found at Hubberton, again based on structural differences. Sadly, my pics were taken at distance in early morning light, so they are not great, but they still suggest that two birds were involved.
The bird in the pic on the left flew from the beach into the root crop at West Angle before flying off inland, the bird in the left is the Hubberton bird. What is instantly noticable on the West Angle bird is the extensive plumes on the neck and mantle, the latter almost reaching the tail. These plumes can also be seen on pics of the bird in flight. Even the longest feathers on the mantle of the Hubberton bird do not, as far as I can tell, extend further than c.half way down the back. Also, the nostrils of the West Angle bird appear to be set in yellow, whereas the nostrils on the Hubberton bird are set in pale grey.
So it could be that we actually had three Cattle Egrets in the county last week? If anybody has noticed long plumes on the mantle of the Hubberton bird then I would be interested to hear of it, but none of my photos (or observations) have given any indication of this. Both the right hand pic above - and the pic of the Hubberton bird on last Wednesdays blog, suggest that the feathers on the mantle of this bird are relatively short.
I guess the take-home message must be that Cattle Egrets are expanding their range, there were good numbers across the water in Devon last winter, and we can probably expect to see them more often in Pembs.