I think John Moxon Nicholas is where Chloe's grandmother went wrong, as I'm not sure that he existed, and if he was born in 1800 is unlikely to show in Cambs FHS Baptism Index 1801-37. Downham baptisms have been extracted onto the IGI up to 1876
Going back from the known to the unknown, which is the only way to go unless you're looking to research someone else's tree:
Herbert Nicholas
Birth Freebmd, Ely registration district which includes Downham, Dec quarter 1900
1901 census
Main Drove, Downham
Trew Moxon Nicholas head marr 35 Farmer
Agnes Annie Nicholas wife 34
Emily August Nicholas dau 4
Bertha D?orris Nicholas dau 3
John Trew Nicholas son 2
Herbert Nicholas son 7 mths
Amelia Sennit visitor single 37 Living on own means
Sarah Jane Moxon servant single 19 General servant
All born Downham
Freebmd Marriage June quarter 1893 Ely reg district
Trew Moxon Nicholas and Agnes Annie Sennitt
1881 census at
www.familysearch.orgMain Drove, Downham
Ann Nicholas head widow 45 b Downham
Emily Nicholas dau 17 b Downham Fen
Trew Moxon Nicholas son 15 b Downham Fen
Herbert J Nicholas son 13 b Downham Fen
John Moxon father widower 70 Annuitant b Downham
Death Freebmd
March quarter 1871 Ely reg district Trew Nicholas age 41
Birth Freebmd
Ely reg district June quarter 1865 Trew Moxon Nicholas. If it were me I'd purchase the certificate to double check on parents' names, given there were other Trews born at the same time
1861 census
Main Drove, Downham
True Nicholas head marr 31 Farmer of 33 acres
Ann Nicholas 25
Next entry
Main Drove, Downham
True Nicholas head marr smudged ?5 Farmer 110 acres
Roday Nicholas wife 70
All born Downham
IGI
Marriage Downham 1 Dec 1860 Trew Nicholas/Ann Moxon Fathers - Trew Nicholas/John Moxon
1851
Fodder Fen, Downham
True Nicholass head marr 56 Farmer 100 acres
Rhode Nicholass wife 58
True Nicholass son unmarr 21 Farm lab
Ruben Forman servant unmarr 14 Farm lab
All b Downham
1841
Main Drove, Downham
Trew Nicholas 40 farmer
Rhoda Nicholas 40
Trew Nicholas 11
Robert Couch 15
All born in Cambs
IGI
Baptism Downham 10 Dec 1829 True Nicholas, son of True and Rhoda Nicholas
IGI
Marriage 10 Dec 1823 Downham - Trew Nicholas/Rhoda Bradfield
IGI
Baptism Downham 22 Jan 1797 True Nicholas son of John and Hannah Nicholas
One thing that's puzzling me is a marriage on 21 Feb 1863 in Downham between Trew Nicholas (father Trew) and Ann Nicholas. I can't work out how this fits in, although in 1881 there's a Trew 40 and Ann 39 living in Downham, but I can't find his baptism c1841.
David