Hi Rambler and Monica
You know what it's like when you've been working on people on your tree and then you decide to look properly at the line following the mother, rather than the one which directly relates to you!!!
I too was just looking at bmds and found the ludlow one, which puts her 4-5 years older than the census' and her marriage certs. The only other possibility was an 1858 one, but in Hereford, not too far away, where later on her husband came from. She does keep stating Ludlow as her birthplace but she could be wrong of course.
What I do like about the one with Mary Pugh is that there is no father, so that throws up the possibilty of her father really being a vet, but her being illegitimate and taking her mother's name. Perhaps he had an affair with his servant? It would make sense of the fact that we can't turn up James Pugh vet, he may really have been called James, but she would have changed the surname to fit hers. (Have other close rellie who did that!!)
It might be a case of sending off for the 2 certs, although the way this is going I'm not sure anything will be confirmed - so it would be a good idea to have to get both girls on each census really to sort them out. (Funnily enough, my ggrandmother in Stoke had the same name as a girl born the same year and place, yet there were no others with that name within 20 years and we had to try to pick out which was which there!!! )
I'm reasonably sure she wouldn't have been born Stourbridge as it's too far away, not far from where I live in fact.
Thanks very much for all your brilliant help and the suggestions, this is getting more intriguing by the minute and there are now lots of possibilities to investigate