Thanks for the info about the marriages of George Taylor in Brampton.
The reason I thought Ellen's sister Sarah may have married Thomas Fullard is because she was one of three Sarahs born in Brampton on the 1851 census who were born around the right time.
I had conditionally eliminated two, Sarah Jinks or Jenks and Sarah Lantaff, because I found the marriages and the previous name was not Taylor.
The earliest child of the six Fullard children christened in Sep 1823 was Thomas born c 1816, then William c 1818, Francis c 1820, George Henry c 1822, and Edward c 1823. Don't have a date for John as he appears to have died before the 1841 census. He could possibly have been the eldest and not at home by the 1841 census of course.
However, I agree that the marriage of Thomas Fullard to Sarah Pick in 1811 is most likely the couple who settled in Thorney.
Your mention of a Sarah Taylor marrying a John Green in 1815 piqued my interest though as Sarah Lantaff had been Sarah Green before she married James Lantaff in 1821 in Hemingford Abbots. He had previously been married to Sarah Daniel who died in 1819. They had about nine children and then he had a another two with the second Sarah.
There is another thread on here where his daughter Elizabeth, with his first wife, married secondly a William Allen after being married to James Gaunt.
I can't find a death of a John Green between 1811 and 1819 on the NBI but may have been in a parish not covered.
I am sure the marriage between Ellen Bott and Samuel Hilliam is John's widow. There is only one Bott family in Huntingdon at the time and she is the only Ellen. Co-incidently Samuel Hilliam was the widower of Ellen's deceased husband John Bott's cousin (not first), Ann Newitt, whom he had married in Godmanchester in 1827.
Denise