Hi
Going on the assumption that the Robert Wilson born in Northumberland is him, I looked at the 1881 census for the same area, and found these.
34 Union St
Newcastle On Tyne All Sts, Northumberland, England
Thomas WILSON Head M Male 38 Newcastle On Tyne Clerk Unemployed
Mary Ann A. WILSON Wife M Female 40 Newcastle On Tyne
James WILSON Son Male 15 Newcastle On Tyne Engine Fitter At Works
Isabella WILSON Daur Female 11 Newcastle On Tyne Scholar
Thomas WILSON Son Male 5 Newcastle On Tyne Scholar
Julius B. WILSON Son Male 2 Newcastle On Tyne
1 Brewery St
Westgate, Northumberland, England
Thomas WILSON Head M Male 47 Bill Quay, Northumberland, England Saw Mill Manager
Mary A. WILSON Wife M Female 43 Corfus B Sub, Greece
James M. WILSON Son U Male 18 Newcastle O Tyne, Northumberland, England Joiner (Appretice )
Mary A. WILSON Daug U Female 16 Newcastle O Tyne, Northumberland, England Music Teacher (Musician)
Emma WILSON Daug Female 11 Newcastle O Tyne, Northumberland, England Scholar
Margaret W. WILSON Daug Female 8 Newcastle O Tyne, Northumberland, England Scholar
Thomas H.M. WILSON Son Male 6 Newcastle O Tyne, Northumberland, England
Florance E. WILSON Daug Female 3 Newcastle O Tyne, Northumberland, England
Ethel J. WILSON Daug Female 11 m Newcastle O Tyne, Northumberland, England
5 Office Row
Burradon In Tynemouth, Northumberland, England
Thomas WILSON Head M Male 51 Fawdon, Northumberland, England Coal Miner
Mary WILSON Wife M Female 51 West Moor, Northumberland, England
John W. WILSON Son U Male 18 Barrington, Northumberland, England Coal Miner
Honour WILSON Daur Female 16 Barrington, Northumberland, England
Mary WILSON Daur Female 14 Sleekburn, Northumberland, England
Richard WILSON Son Male 7 Burradon, Northumberland, England Scholar
There were two marriages for a Thomas Wilson and Mary's that I found who were married before Robert's birth.
THOMAS GASS WILSON
MARY SANDWITH
Marriage: 17 SEP 1854 All Saints, Newcastle Upon Tyne, Northumberland, England
THOMAS WILSON
MARY MINICAN
Marriage: 01 SEP 1855 All Saints, Newcastle Upon Tyne, Northumberland, England
Possibly one of these will look like the name on the document you have.
Hope this helps.
Janice