Deaths have to be registered in the district where they occurred, but obviously, the burial or cremation doesn't have to be in the same place, or even in the same district.
So all you can tell from CAMDEX is the district where the person died, and the death certificate will have no information about the burial.
The death certificate itself will give you a more specific place for the death - which may help you to find where the person is buried.
Ely district covers several parishes:
http://www.ukbmd.org.uk/genuki/reg/districts/ely.htmlIt may be that the people you are looking for didn't actually live in Ely - for instance someone who lived in a nearby village might have died in hospital in Ely, but been buried in their local churchyard.