What was it you wanted to know?
George says in 1891 that he is of Wolston and he seems to be the only one born at the time.
The new family search point to parent being as you say being Thomas (born 1827 Wolston) & Mary along with another son Thomas in 1850 at Wolston.
To find them in the census record 1851 you need to put the name as Fields with an 's on the end of Field
link for ancestry http://search.ancestry.co.uk/iexec?htx=view&r=5538&dbid=8860&iid=WARHO107_2069_2069-0117&fn=George&ln=Fields&st=d&ssrc=&pid=9408696
It's a bit faint, but I see next door is William and Esther about the same age so this may well prove to be a brother of Thomas
The 1841 (again search for Fields) shows him with his parents Marshal Fields and Sarah (What a great name Marshal Fields!)
Hope this helps