Hello Barbara,
Yes i had that 1851 census.
So you do not know who William Rolley's, parents are.
It also looks like James Allan, died 1870. in Dreghorn, Ayr, aged 60 years. of course there are a lot of James Allan's, in Ayrshire, this one however is about the correct age, i suppose you do not have Isabella Watson Allan's, death certificate of 1874. which would give parents names and would also state if James Allan, was deceased at that time indicating a pointer to the above death i mention.
Here is a indicator to whom i think are William Rolley's, parents and siblings at this time, 1841.
Kirkoswald, Ayrshire,
Adress Kirkoswald,
Rowley Alexander M. 35 years, Agricultural Lab. born Ireland,
Rowley Helen, F. age 30 years, born Ireland,
Rowley John, M. age 9 years, born Ayrshire,
Rowley James, M. age 6 years, born Ayrshire,
Rowley Robert, M. age 3 years, born Ayrshire,
Rowley William, M. age 1 years, born Ayrshire,
Rowley Alexander, M. age 13 years, born Ireland.
The 1841. census in Scotland, does not supply relationships to the people in a household.
You will also notice the spelling of the surname, however William Rolley, states on the 1881. census
that he was born in Kirkoswald, Ayrshire, and is aged 40 years on that census.
However William Rolley, does not seem to have a son name Alexander, however he has a daughter Helen, sons James, and Robert and of course William.
I still think this is your William Rolley, in 1841. with his parents and brothers.
His mothers name i think is Helen Best.
The only way to prove this is to get William Rolley's, marriage certificate 1866. Dreghorn, Ayr. which would confirm his parents names.
Regards,
Jonn.