I see William married Elizabeth Hazelwood in 1825. And the most specific Census for William's place of birth is 1851 - which says born Little Bourton, not Great.
GREAT BOURTON, (and LITTLE BOURTON) a township in the parish of Cropredy, hundred of Banbury. The ancient chapel, dedicated to St. Michael, is occupied as the school-house. There is an Independent chapel in Great Bourton, and a Wesleyan chapel in Little Bourton, which is 1 mile nearer to Banbury…….about 3 miles (5 km) north of Banbury….. largest settlement in the civil parish of Bourtons. Population in 2011 Census, was 614.
(Genuki & Wikipedia)So the population was small - still is - and one might be entitled to hope that back in the day, any CURTIS found born in Great or Little Bourton are likely to be related?
My suspicion falls squarely on these events - looks like a chain to me (well the last bit maybe taking it a bit too far, but ..... ):
BAPTISM 1796: Baptism at Banbury, St Mary, Oxfordshire on 30 December 1796
Of Neithrop, Baptised : William Amritt, base son of Sarah CURTIS.
'Amritt' could well be the surname of the father. It was fairly common to give an illegitimate child the natural father's name as middle name. Would be worth investigating Bastardy Bonds.MARRIAGE 1808: Banns between
Nehemiah Dunn and Sarah Curtis, both of this parish of Cropredy, called on July 7, 10th & 24th, 1808. Married by Banns on 25th July 1808. Signed by Nehemiah DUNN himself, and the X Mark of Sarah CURTIS in presence of Daniel Hunt & Martha Alitt.
CENSUS 1841 - Bourton:There appears to be a number of dwellings, which each have multiple separate families living within ( that's if the enumerator has deployed the / and // marks correctly). There are also a number of Hunt, and a lot Ellitt or Allitt families around too.
HO107 Piece: 873 / Book 10 / Folio 7 / PG 10
//
Nehemiah DUNN 60, Ag Lab = Y
Sarah DUNN 50, - Y
Kitty (?) DUNN 10 - Y (female)
/
Thomas CURTIS 60
Mary CURTIS 60
John CURTIS 30
Thomas CURTIS 25
Mary CURTIS 20
/….
Not a million miles away from the Nehemiah & Sarah, is your William in 1841:
HO107 Piece 873 / Book 10 / Folio 9 / PG 12William CURTIS 40, Ag Lab
Elizabeth CURTIS 35,
James CURTIS 15,
George CURTIS 12,
Sarah CURTIS 10,
Ann CURTIS 7,
CENSUS 1851 - Village of Great Bourton: Your William is here:HS 62, HO107 - Piece: 1734 / Folio 113/ PG 15
Head: William CURTIS 50, Ag Lab, b Little Bourton
Wife: Elizabeth CURTIS 47, b Cropredy
Dau: Ann CURTIS 17, b Gt Bourton
Dau: Emma CURTIS 7, b Gt Bourton
And 5 households away on the Census 1851 is Nehemiah & Sarah:HS 67 HO107 - Piece 1734 / Folio: 114/ PG 16
Head: Nehemiah DUNN 77, Pauper formerly Ag Lab, b Gt Bourton
Wife: Sarah DUNN 67, b Gt Bourton
(the family before them are ELLITT)
DEATH 1853: Nehemiah DUNN, registered in Banbury
DEATH: Jun Qtr 1852 or Dec Qtr 1861Sarah DUNN, registered in Banbury.
CENSUS 1861 - Village of Great Bourton: Your William is here:Head: William CURTIS 60, Ag Lab, b Bourton
Wife: Elizabeth CURTIS 55, b Bourton
Dau: Emma CURTIS 17, b Bourton
I think the widow of Nehemiah DUNN is the one who died late 1861 and this could be her
CENSUS 1861: Constitution Hill, Neithorp, Banbury: RG 9 Piece 920 / Folio 66 / PG5
Visitor: Sarah DUNN 77, b Bourton, Oxford (no marital status given)
Visiting the family of John TUSTAIN age 36, whose wife Hannah is 38 and born Gt Bourton.
There is a TUSTIN (not spelled TUSTAIN) family on same page as Sarah. She's at the top of page, they're at the bottom of page and carry on over to next page. In their household is a lodger thus:
Lodger : James ARMITT age 86, widower, Boot & Shoe Maker, b Banbury.
Wouldn't that be wild - If James ARMITT was William Armitt CURTIS' father and William Armitt CURTIS is your William, and Sarah DUNN nee CURTIS is William Armitt's mother!!!
Cheers
AMBLY