The Peter Cameron, mason, found above in the 1841 census at Tomintoul, is still there with his wife in 1851. Both are born in Kirkmichael, Peter is still a mason and aged 55.
If he is the right person, his brother would perhaps be born in the same parish. The 1851 census shows a Donald Cameron, aged 59, born Kirkmichael, a farmer in the parish of Kirkmichael (mostly pasture). His wife is Charlotte.
The 1841 census shows this same Donald Cameron at Tombreck, Kirkmichael, as a mason. He has six daughters and one son, Peter. It looks as if the mother has recently died. Charlotte Middleton is a servant keeping house and looking after the children. Donald must (as often was the case) have married her as her age and name fits with the 1851 wife.
If this is uncle Donald, he would have been about 73 when his nephew died and had perhaps seen out a 19 year lease and retired to Elgin.