I have found elsewhere that James was not found living with parents on the '51 and '61 census, could it be either that parents were deceased, or that mother wasn't married to the father of James?
"1851 census as the nephew of Alexander (age 56) & Mary Roy(Age 63) of Belnaboth he was 6, & in 1861 census he's listed as the grandson & scholar although his age is now 13 (not 16)"
Assuming of course this is the same James.
Jamjar
Added: Belnaboth 1851
Alexr Roy Head Mar 56 Farmer of 6 acres employing no Lab Aberdeenshire, Glenbt
Mary Roy Wife Mar 63 do, Cabrach
Elizabeth Roy Daur U 17 Farmer's daur do, Glenbucket
George Farquharson Nephew 8 Scholar do, do
James Gordon Nephew 6 do, do
1861
Same as above, but no George and Mary Dawson granddaughter added.
1871
Alexander Roy Head Widr 76 Farmer of 9 acres of which 8 arable
Elizabeth Roy Daur Unm 35 Farmer's Daughter
Mary Dawson Grand-Daur 16 - illegitimate daughter of Elizabeth
William Davidson Head Widr 32 General Merchant
Babtism: DAWSON & ROY – December 1854 – Baptized by the Revd Wm Adam Smith Minister of Towie MARY – the illegitimate child of James Dawson and Elizabeth Roy in this Parish.
1823 ROY - May 12 - Baptised Mary Daughter to Alexr Roy Belnaboth