No Ann Simpson marriage anywhere on the IGI to a Wilson, within 10 years of the baptism (though I did say Oxfordshire is not well covered) - no Ann Simpson marriage to anyone in Fifield. I was already ahead of you on a Wilson move to Harbury and had checked the National Burial Index for Wilsons, at the same time as I checked for Finches - nothing. I've gone back and checked for Simpson - still nothing (Harbury only goes up to 1852).
Fifield is not on the National burial index - but I have not detected a single Wilson event in Fifield on the IGI (but see below on start of IGI coverage for the parish).
Ann Simpson of Fifield had a child before Avice - John Hayward Simpson in 1796, which might give an indication of his father's surname at least. No other Simpsons baptised in Fifield around this time (but the IGI coverage I think only begins in 1794). No marriage for a John Hayward Simpson on the IGI, or a death of the same on FreeBMD. On the 1861 census there is a John Simpson 60 born Fifield an ag lab. with his wife Sarah 56 born Charlbury Oxon. No other Simpsons born Fifield or in Fifield or Wil(l)sons or Haywards and no Avis or Avice, but 1861 is a long time after the events. No John Simpson after 1861 and no death registration on FreeBMD.
However,
and here comes something much more interesting, there is a Hannah Simpson marriage 15th October 1812 in Harbury to a William Masters. The 1841 census entry for this couple has already been posted with Hannah approximately 50 born in county, so to young for a son in 1796.
Undeterred I checked the 1851 census for Hannah Masters and found this
HO/107/2077 Folio: 98
Mill Street, Harbury
Hannah MASTERS Head Widow 66 Farmg 11 Acres Emp 1 Lab born Fifefield-OXF
Which would give her a birthdate of circa 1785, still to young for baptisms of a child in 1796. As far as I can tell Hannah Masters and Mary Finch were the only two people born in Fifield present in Harbury in 1851. Ditto 1861.
RG9 2241 folio 72
Chapel Street Harbury Warwickshire
Hannah Masters 79 born Fifield, Oxfordshire, Head Widow Formerly the wife of ag lab
Her age is improving as she now has a birth date of circa 1782 which could just squeeze her in at 14 for a baptism for 1796, though its a tight fit. After that she is missing and I can't find a death registration for her on FreeBMD.
Other than Avice Simpson taking her father's surname of Wilson (he doesn't appear to be in Fifield parish as there are no Wilsons appearing in the parish register) I can't think of another easy explanation for her surname (I can't find any previous marriages for her, though of course she might have married as a Mary- none as Hayward either). I think it would be very unusual for an illegitimate daughter brought up by her Simpson mother to carry her father's surname, unless perhaps her mother had a Wilson connection? If there is a bastardy bond for Avice Simpson in Oxfordshire Record Office that might help if the father's name proves to be Wilson. It gives no help at all with explaining a late name change to Mary. (Ann/Anna/Hannah is much more standard)
Louise says somewhere previously in her messages that she has researched Stephen Masters family, the father of Avica's son. Is there a connection with William Masters of Harbury, the husband of Hannah, since Stephen Masters was baptised 1805 in Staverton Northants?
The only burial I can find for a William Masters on the National burial index does not give an age - 25th August 1848 Harbury Wesleyan (nothing on FreeBMD).
I cannot find on the IGI a baptism of a William Masters in Harbury but I can find several possibles for a William in Staverton.
So was William Masters of Harbury, an uncle of Stephen's?
In which case married Stephen may very well have had an illegitmate child by his step cousin (I think that offically would be the relationship). It also means along with the half and step Finches and the half Masters of Stephen's children, there is now the possibility of a half Masters aunt, a child of William Masters and Hannah.
The IGI for Harbury lists only one baptism for a Master
MARY ANN MASTERS
Christening: 07 MAR 1828 Harbury, Warwick
Age at Christening: 14
Father: WILLIAM MASTERS
Mother: ANN
and a marriage
MARY ANN MASTER
Spouse: EDWARD MARTIN
Marriage: 10 APR 1834 Harbury, Warwick
There were Martin children on the 1841 census with William and Hannah.
As I think the IGI Fifield register coverage only starts in 1794 (according to my Phillimore Atlas and Index of parish registers) perhaps the early period and Hannah's baptism may reveal Wilson connections? - Fifield registers appear to go back to 1700 (see Phillimore quote above) but JAP says that the Bishop transcripts - the copies of the registers which were sent to the Bishop, survive before that starting in 1669.
The transcript of the parish registers themselves can be bought on fiche from Oxfordshire Family History Society for the grand sum of
Fifield, Oxon - - - - - - - - - - - - - - - £2.10
http://www.ofhs.org.uk/On their website you can check out their other search facilities, - payment is possible online by credit card
Regards
Valda