Hi again Julie,
I must thank you for bringing Mary Ann Isgar to my notice. I'm very fortunate enough to be in contact with another of William Isgar's great great grandaughters and we're working together. She's confirmed with an elderly relative that this is our Mary Jane as she purchased the death certificate many years ago and it was a mistake with the name. Mary J (or Mary A) looks to have died in childbirth as a baby Mary Ann was with her.
So, thank you again. A lesson in seeing the larger picture!!!
Very best wishes