Was William a shoemaker? If so he is on his own in the 1851 census living at Couching Street, Watlington, Henley, Oxfordshire
Marital status is blank.
He is a master shoemaker employing six men and two women.
If the death of Mary Knobbs that Heywood has found is William's wife, then William should have had widower as his marital status on the census record.
There is no-one else listed with him at all, so presumably his son is with the Richard & Rachel Shaw that Heywood also found.
This is the death that Heywood found from the GRO website:-
KNOBBS, WILLIAM Age 31
GRO Reference: 1852 M Quarter in HENLEY IN THE COUNTIES OF OXFORD BERKS AND BUCKING Volume 03A Page 307
That gives him a birth year of 1821.