Hi,
There is a public tree on Anc….y showing a J W Knight with a birth date of 8-2-1896 in Battersea, Middx and married to Elsie Jesamine Radway on 4-4-1920 in Tottenham, Middx. They are showing the exact same date & place of death as you list.
They are also showing a photo of J W K and there is also a copy of the original marriage entry showing the full details.
Where are you getting your info from? as it seems the dates are identical to what you mention.
It could be they are mixing up the various “Knights” and coming to the conclusion they are all the one family.
On FreeBMD there is an entry for a JWK birth registration in the Mar ¼ 1896, Fulham Reg. Dist Vol;1a, Page; 333. Could this be the one?
Alan