he appears to be the only child of Wm + jane I can't place in 1841 IoM census - there is will for a Wm Gill in 1823 Lezayre (in Episcopal wills) if this is father Wm then might confirm as Wm junr is eldest son + if any property to inherit he would be heir
Tho' Jane als Fargher didn't die until 1846 she doesn't appear to have left a will - she is with her son Ewan/Hugh who is miller at Kella mill