I'm intrigued by the birthplace of George's eldest son, William.

I'm assuming that George and Jane spent sometime in the Portsmouth area before ending up in London.

I have looked for a baptism in both surnames to no avail.

I used to live in Southsea and most churches there were built later than 1840-ish as far as I know. The exception is St Thomas (the Anglican Cathedral) but that's in Old Portsmouth, not Southsea (if I'm being pedantic). No baptism there anyway.