Jonwarrn,
I had believed Mary Ann Swinburn to be the previous owner of The Isle of Man but, from your information, I can she was his 22 year old niece and he had obviously put her in to manage the beerhouse whilst he run the Shield Row Hotel a couple of miles away.
All of the other details you supplied fit nicely with what has already been discussed here for instance, the fact that his son was the publican by 1891. As for Henry Tiplady, he took over management (if not ownership) of the Shield Row Hotel some time after John Charlton's death. I have no idea where he was in 1871 but there were four pubs in Annfield Plain at that time.
Neville