Could she be Ann Boyer daughter of John and Ann of Ashburton? baptised 1805, death in New Zealand at 92 as Ann Webb would work.
What a story!!! you could write a book on this one!Left with 4 children under 7 husband drowned!marries again, more children.
Back to Stoke damerel marriage, this couple seem local, he is gardener to landed family in the parish at Swilley House, the landowner james furneaux sponsors the couple and the little ones to New Zealand on the Duke of Roxburough ship. WHY? He had a good job, cottage provided I expect.
Perhaps she was a servant there too.
Very interesting bit of research.