To save you a job I can let you know that Elizabeth HUXTABLE was indeed a spinster when she married, or so the register says. Tony and Linda KNIGHT did a look-up for me. She made her mark and Robert TAW signed. He was a gunner by the time of his death, if he is indeed the man who made the 1837 will. Another contact told me he served on the Montagu(e) which was built at Chatham. I will have a look and see if I can unearth the evidence.
If you do manage to get to Portsmouth Records Office it would be wonderful if you could check the early baptisms to see what it says in the register. I know the IGI doesn't tell us such details but I wonder if it says mother Elizabeth HUXTABLE, reputed father Robert TAW, or whether Robert himself is going under the name HUXTABLE.
All the best