The 1891 Census record where he is in London, Ontario working asa bookkeeper in a Sherrif's Office must be this one: link
He is given as age 64 born in England, Wife given as Permelia age 45 and son Henry age 18 both born in Ontario.
That family appears to correnspond with the marriage register entry at Wingham, Huron, Ontario dated 28 Sep 1859 for a Joseph Nicholls, age 30, born England, residing Goderich Twp. son of Thomas Nicholls and Sophia Hudson who married a Pamella Brace, age 21, born and residing at Goderich, daughter of Henry Brace and Margaret Fisher. (Archives of Ontario MS248, Reel 8).
A number of other children appear in the 1881 Census at Wingham where Joseph is listed as a carpenter at age 52 (or 62) and Pamila is age 38:
William age 20, Henry Joseph age 9 (age 19 struck out), Alfred John age 17, George L age 15, Mary Ann age 13, and Charles E age 11. Also an elder of wife Pamella is also cohabitating.
The same family is found at Turnberry Twp., Huron Co. in the 1871 Census here and here another child not already accounted for by the 1881 Census record is also given, daughter Sophia Age 9.
In Census 1861 they are still residing at Goderich Twp.
The Death Register at London City, Middlesex County gives his date of death as 3 Nov 1906, age 77 years, 6 months. address 462 York St. (Registration 549 stamped 018464; Archives of Ontario MS935 Reel 126)
The Find a grave entry indicates a birth on 17 April 1828 and indicates he was buried at Woodland Cemetery. This date of birth is also that recoreded on Census 1901. This census record also indicates his wife might have actually been born in the U.S. and arrived in Canada as an infant. The immigration date for Joseph himself appears ot be 1855,
There is a nearly perfect Match for a Josph Nicholls, son of Thomas and Sophia baptised at St. Martin in the Fields, Middlesex Co., England on 17 Jun 1827. This record gives his father's occupation as sailor and their residence as King (st?) (Page 297, scan counter 00335, DL/T/093, Item 048)