Hi Joanna,
I've looked through the baptisms and from 1819 to 1812 there is only the one Eliza Seaton.
24 May 1812 Eliza Seaton daug of Francis and Sarah, privately.
The only marriage that I can find between a Francis and a Sarah in Huntingdonshire is in 1783 at Huntingdon AS & St J (All Saints and St James?) Ruth