When I searched on FindMyPast I put surname Barrand and ticked the box for name variations, but it didn't throw up Barron. I've just done a search for any Barron's and there aren't any on Lincolnshire Baptisms on Findmypast, I even did a general search of the whole site and nothing came up. I think you're correct that some of the records are missing, or maybe some events were just not recorded, as in the quote I gave
The register for the two following years in the absence of the vicar is imperfect, the names given in to ? are as follows.
I checked on Familysearch.org but there is no Sarah Barron.
I've just had a quick check on FreeReg and there is another son of Joseph and Elizabeth Barrand called Edward, baptised 5 Mar 1758 at Heydour and also the Sarah Barron you found. It's past midnight here, so I'll check again more thoroughly tomorrow.
Lizzie
