Odd that the 1824 Pigot's that I have in a membership program didn't show up at all. They must of missed it, I makes me wonder how many other omissions/errors there are?
1810 Wm. Gavin would of been 18-20? If he returned to Ireland and took up farming there are quite a few Wm.Gavin's in the Tithe Applotments. Perhaps too many to be looking for birth records through the Foundation. If you have a reasonable birth year you might be able to narrow down possibilities (if the church records survived)just by searching William Gavin's born (est 1790)as an ALL Ireland search. You can also search for -blank McMahon- with father Bernard McMahon, Tyrone and get all his Bernard's children without any more information than that.
That is an interesting story for sure.
Another program which I used to subscribed to had
British Army records, there is a link via the Archives at Kew. You can search the BA records with just a surname.
You can get a '72 hrs. or by the month' membership. If you want the name of this subscription you will have to contact me at email@example.com
as rootsweb don't allow the use of commercial/fee paying websites.
Good luck. Annette