Hi,
I think that William's birth is registered as KEENE,
William James KEEN Mar Q 1857 Blean 2a 557
Baptism
William James KEEN
15 Mar 1857
Herne, Kent
Mother: Caroline KEEN
This would fit with the 1861 census age of 4. Looking at the 1881, 1891, 1901,1911 census it looks like William reverts to the name KEEN.
If so was Peter his father? I wonder this as Emma Jane b. Jun Q 1859 is registered as a PORT. When did Peter's wife Eliza die?
I think the William James PORT born Mar Q 1858 might belong to James and Anne PORT from Whitstable.
Regards,
Daisy