I can't find a death certificate for my G G Grandfather a Joseph White, information that I have, suggests he died between 1881 and 1891. This I have based on the fact that my G G Grandmother was living alone with her son George (my G Grandfather) and declaring herself a widow in 1891, she remarried in 1900.
The only match that showed any promise was a Joseph White that died in 1896. The age was right, but the occupation was wrong. The informant was his daughter an E Thompson (my G G Grandparents had two children an Emily and a George). It's possible that the informant, E Thompson is an Emily White who married a "Thompson", but I can't find a marriage to support this. Then of course 1896 is 5 years after my G G Grandmother first declared herself (to the best of my Knowledge) a widow!!. Lastly when George married in 1902, one of the witness's was an Emily White!!!!
Their son George (my G Grandfather) was born some where between mid 1876 and march 1877. His marriage certificate in 1902 and the CWGC database stating he died in March 1915 aged 38, support this, but even after three years of searching I cannot find a birth certificate for him.
Last year I joined a family history/research class, not because I thought they could teach me anything (it was a beginners class). But so I could pick the brains of the tutor who had been doing family research for 35 years. A Long time before the creation of the internet and computers became affordable. I asked him questions very similar to yours, based on the information above.
He said as far as births were concerned, conservative estimates show that as late as the 1870's /early 1880's as many as 10/15% of births were still not been registered. As for deaths there is no legal requirement (or there wasn't) for a man's marrital status to be declared on a death certificate, which may not be known anyway, especially if the informant wasn't family. Informants could give (and did give) any name they wished, they didn't have to prove who they were. There was no reqirement for a full name or proof of indentity to be given. Even if it were, how it was recorded (initial or full name) was down to the person who filled out the original death certificate, the doctor and /or the registra. The registra can only give you or I the information that is on the certificate. If it was given wrongly or recorded wrongly, then in all probability we may never be able to tell. I will keep searching for now, but the tutor did say there will come a point where you will have to accept that there is no more information to be found, something that has happened to him more than once, while doing his own family tree.
Did Harriet have more than one name? I have a female relative who' names were Emily Mary Margaret. Depending on what I assume was her mood at the time, I have found her recorded as either Emily, Mary or Margaret. It has made un picking her history, quite interesting to say the least!!!