Hi Tony,
It is always best to double-check everything before passing it on, because I could easily have made a typo or mistaken assumption.
I meant to let you know that I posted some messages for Mary M last year about your William's probable eldest brother John b.1766, d.1850 of Ballasloe.
See: www.isle-of-man.com/genealogy/messageboard/index.pl/md/read/id/551123
In an earlier message to her I said that Constance Radcliffe wrote "the old Ballasloe house still stands by the road" (1979).
Mary replied: "I drove past Ballasloe House & Old Farmhouse they are beside that same road leading from Hiburnia to Maughold Church".
So somewhere for you to visit next time in the IoM!
Sue