Ok, in that case, 1851 makes more sense regarding James Blair:
John Blair 42, Farmer Of 51 Acres Arable And 36 Pasturage
Margaret Cameron 50, sister
Isabella Blair 35 sister
James Blair 31, nephew
Jane McDonald 14 niece
Archibald McDonald 10 nephew
Address: Tomdow, Abernethy and Kincardine