Hi Trev
I have spent abit of time looking at this, the hand written entry is in Q1 of 1873, it says Maria Bampfield 67 Birmingham.
I looked at the 1871 census for your maria and found her, then I looked for any other Marias including a Maria Bampfield anywhere in england. the only maria Bampfield is living in marlybone in her late 40's, with a husband emmanuel. I think this is the daughter-in-law maybe that you mentione before.
Your Maria I can find in 1861 living on an army pension, and born Chichester Sussex.
I wondered if she had reason to travel to Birmingham in the winter of 1872 and died there, she would have to be registered where she died, maybe there was a delay in registering her death because of some strange circumstance, maybe she was not identified initially? The age is 10 years out, but the age is given to the registrar by the person who attends to register and maybe they just got it wrong. The name of the informant on the certificate and the address of the informant or occupation/relationship to the deceased may give you a clue, I think it is worth sending for certainly.