Thanks for looking Geoff and Dinor.
The 1778 marriage of William Blackburn to Mary Barsley in Boothby is mine. It's this Mary Barsley who I'm trying to track down and think may have been baptised in Digby in 1758, daughter of Thomas & Mary Barsley.
I'd come across the 1751 marriage of Thomas Barsley and Elizabeth Blow in Leasingham before and discounted it. Perhaps I was a bit hasty! I'll have to consult the map to see how close Leasingham is to Boothby Graffoe etc. I suppose it's possible that it's another parish clerk boo boo and should actually read 'Mary Blow'!!
I did manage to find another child baptised to Thomas and Mary Barsley in Digby - Ann in 1756 - so it's possible the Leasingham couple moved to Digby.
I suppose the sensible thing to do is to try and find any children baptised to Thomas and
Elizabeth Barsley in or around Leasingham. That would help to establish that they were a separate couple altogether!
Have you got baptisms as well as marriages, Geoff? Pretty please!

Jill