I think that the Ancestry tree may be right despite the disparities, because I note that on the 1861 census, ( RG9/447 Folio 29 Page 6.) Bayford Harriet is married to a Joseph ALLEN and that she is living in Coulsdon, Surrey, so it would appear that your Harriet was indeed born in Bayford. It would be quite a coincidence for 2 Harriett PALLETTs to marry 2 Joseph ALLENs!
This still leaves us with a problem though doesn't it, because the marriage certificate gives her father as William and the baptismal record gives her father as James. As there are other baptismal records for James and Mary's children at Bayford, it may be that the marriage certificate is incorrect. The Vicar/Registrar may have got muddled or her father was William James, but he preferred to be called James for example.
Why not contact the Ancestry tree holder and ask why they decided to give her father as James and not William? They may have already encountered this problem and found an explanation.
Rick
