If they were raised in an orphanage one would assume they were registered, particularly after 1875 but if they were a foundling they might be surnamed after the place where found, saw that myself in records, or a person or policeman who found them, I have seen baptisms showing a child was a foundling
I am sure someone with more knowledge than me might come up with a suggestion
Can you give details on here?
Louisa Maud
PS, IS HE THE PERSON YOU HAVE ALREADY MADE A POST ABOUT ?