Hi Steven
James Snr.'s death I am struggling with post 1855, may have died before this date (which means there will be no death cert to be found for him

).
Possible death for William's mother in 1871 in Elderslie, Renfrewshire. There is an Ann Quail/Matthews who died that year with a birth year of 1826 which is a possibility.
What did you mean about possibilities for 1861 in the censuses? Which one are you trying to find for that year? We had a possible for mother Roseann remarried to John Quail with her children or the likely entry for William with his mother's family.
Monica