thanks to both.

I can imagine the very pale looking almost 'spats' part of the ankle area must have picked up a lot of mud/grime in view of the condition of roads etc. in the 1880s - the heels look very similar in many of the Victorian shoe/boot designs.
As you can imagine with a public oriented institution such as The National Archives - they are very conscious of being seen to be unbiased and non-discriminatory to all forms of life - so they probably try to allow nature to take it's course in many cases, although I'm aware that this summer they have removed at least one cygnet for health reasons, although sadly believe another has died.
Most of the time Rodney is the sole heron on the ponds at Kew, it's only very rarely that he has a companion. Have to say that apart from small fish I'm not really well versed on his diet, but apparently it does seem he's not averse to baby birds, unfortunately.
It's remarkable to see that whenever I visit, almost without exception he is standing in virtually the identical spot.
Herons are not uncommon in the northern parts of Surrey where it abuts the Greater London area - probably the wetlands which help - the remainder of the county is quite dry due to the chalk etc.