Thanks to all those who have looked at this since I was on yesterday.
The 10yo Fanny Fairy in St Neots with mother Charlotte I beleive her father to be Joseph as there is a marriage in St Neots in 1828 of Joseph Fairey & Charlotte Townshend of Eaton Socon. I think this is the Fanny Fairey that married Samuel Staughton.
I am going to hang on to this discussion as there is quite a chance that Joseph fits into my Farey line somewhere.
So if I back track then, this isn't the Fanny Fairey I am looking for. The one I want was born late in 1837 and was last seen with her paternal aunt Elizabeth Irons (nee Farey) in 1851.