Hi Kris,
I agree with you that Mary was probably unmarried. I think the older sons might have been registered under their father's name as I know before 1850ish this happened sometimes even if the parents were unmarried. It could explain why Samuel seems to be the only birth I could find as he is registered in his mother's name with Lock as a middle name, round about the time the law on registration of illegitimate births was tightened up.
I am going to look for Robert and William's marriages as well to see if their fathers match George's.
I'm not giving up yet!
Debbie
