Looks like James remarried.
1861 census,
21 Ribton Lane, St. Bees, Whitehaven,
James McKay, 47, Cordwainer Master, b. Scotland,
Isabella McKay, wife, 36, b. Whitehaven,
Robert McKay, son, 3, b. Whitehaven
RG 9/3946/45/20
1871 census,
9 Swinburn Court, Whitehaven,
James McKay, 60, Shoemaker, b. Scotland,
Isabella McKay, wife, 40, b. Whitehaven,
Robert McKay, son, 14, b. Parton, Cumberland
RG10/5253/67/31
There is a marriage on FreeBMD in Whitehaven, June qtr 1855 of a James McKay. One of the two possible brides is an Isabella Hume.
Alan.