Hi Jane
Many thanks for your quick response. James was a mariner according to his children's baptisms, so that was from 1818 onwards. His last child, William, was baptised 30.10.1829 but died in the workhouse in 1834, just seven months after James's wife, Sarah died there ... so I think James must have died sometime after 1829.
That just gives a time span of 1818-1829 ... but not knowing his age, I can't tell how long before then he was a mariner.
Sarah Gambrill came from Nonington, so it's possible they were married there rather than St Mary's and I suppose it's also possible there were children in that area before the ones I've found in St Mary's. Sarah was born 4.3.1786 so I'm tempted to think that she started her family before the age of 32.
Any pointers you can give me with be much appreciated.
Chris