Hi Mike
iirc you use Ancestry for 1939 Register ?

Using the FindMyPast free-search I can find the following which may be worth your following-up (sorry, don't have a full subscription).

1939 Register Transcription (Preview)

Harris Household Erith M.B., Kent, England
First name(s) Last name(s) Birth year
Jessie E Harris 1874
Henry Harris is also on this record.

However, when searching again for our particular Henry (ie born abt 1869), I cannot find him in the Erith records.... Harris appears to be quite a common name in Kent.
??

Hope this helps.

ps I wondered why Olive sadly died aged just 30, but cannot find any mention in the BNA old papers site.

??