Alan,  Where do you get your info on Mary McCauley (1767 - ?)?  My GtGtGrandFather was Alexander McAulay (1782/6 - 1860) from Portnahaven.  His parents were Gilbert McAulay  (17?? - pre 1860) & Janet Robertson.  There is a Gilbert McAulay at 4 Portnahaven in the 1811 Tenants List, and I believe (cant find it at the moment) Gilbert was at the same address in the 1797 lists.  Possible connection??
Regards
Michael G Mearns