Thanks for the info - Rose actually died in Bexley, it appears - and the links, Casalguidi. I've just tried the parish registers (I wish we had some of the Welsh ones online), but with no joy with the marriage. And there are no burials in the Gravesend ones, so I couldn't go down that road for an exact death date.
The reason I went for the birth cert was to confirm that it was indeed my Charlie Hazell. I'll give the Dartford paper a few days to see if they respond - I only emailed them yesterday - and if there's nothing I might go for the death cert.
Thanks again,
Gareth