William's age throughout the Census 1871, 1881, 1891, 1901 - and his death age in 1913 in Durris Kincardineshire, are all consistently reporting he was born around 1846 in Culsamond, Aberdeenshire. He was a Slater by trade.
This could be him :
1851: Address: Jimpac, CulsamondJohn McROBIE 64, Inspector Of Poor & Ag Lab, b Culsamond, Aberdeenshire
Wife: Jannet 66, b Culsamond, Aberdeenshire
Dau: Isabella 25, Dressmaker, b Culsamond, Aberdeenshire
Grandson: William 5, Inspector's Grandson , b Culsamond, AberdeenshireThis is the same 1851 family, in 1841:
1841: Jimpie, Culsamond, Aberdeenshire
John McROBIE 50, Auctioneer
Jean 50
Alexander 25, Farmer
Isabella 15
John BEATTIE, Lodger, 5
Jean MIDDLETON 10
The wife/mother of the 1841/51 household is Jean/Jane WILSON. Son Alexander's baptism is on SP for 1814 Culsamond. The daughter Isabella married Alexander ADAM in 1859 in Culsamond.
In 1861, Jimpack Culsamond.
Head: John McROBIE 74, widower, Retired Farmer, b Rayne Aberdeenshire
Son-In-Law: Alexander ADAMS 48, Slater,
Daughter: Isabella ADAMS 36, Slaters Wife & Dressmaker.
Haven't found William in 1861 though

When he married Mary in 1868, who were the witness and what was his address?
Cheers
AMBLY