i have searched the obvious places i.e. the bmd (up to 1920) the CWGC, the national archives and Worcester RO for Attwood via A2A
i have not searched overseas deaths
or the BMD after 1920
or the NBI
he could well have just been registerd under Charles Attwood, there are many of these
he may well have died away from home and therefore registered as an unknown male, the PR's sometimes give further dteials i.e. aged around 31 for example but obviously you will need to know wherehe died to locate him and this we don't
if he died in his home parish he would not have been registered as an unknown male. - that just leaves some 100's of other parishes

if Harriett died suddenly then there would have been an inquest i wonde rif you can get holdof the inquest papers this will tell you if Charles was still alive at the time ofher detah, as she is listed as wife of Charles it is most likely that he was.
Did Charles leave a will? you may be able to locate it if he did and then this will obviously narrow his detah date down somewhat.
a persons idetity at deathmight be different from that at the time his or her birth was registered fromal name changes are not obligatory and there are no indexes of same.
someone dying away from his / her home parish may make positive identification difficult fromt he indexes esp. if the name was common.
given ages at detah may be wildly inaccurate as they might have ben guessed bythe informant, people often had noidea of their real age or lied abou them.
i wonder if Harriett has a headstone, churhyard and cemetery registers will reveal who purcased the plot, and also if there are other family members interred in same
local press announcements i.e. obituary columns and funeral notices inthis casemay reveal further clues (for Harriett)