joemc,
I think I may have found what happened. I looked up the tithe applotments for Burry Meath on the National Archives site, and on the last page there is a John Boyd with no townland beside him. If you click on his name you find a page with the breakdown of the tithes. Against Drumhaggart and Gortcormacan there is only untithable land, so the residents mustn't have had to pay tithes.
Thanks again, as I would never have thought it would have been under Meath.
Regards