Not all electoral rolls survive, so it's entirely possible he survived past 1918.
I have electoral rolls for some of my rellies, from 1907 - 1935, and there are quite a few gaps. So do not assume he died close to 1918, but I suppose he could have.
You will need to find his death, to ascertain his age, and purchase the death cert. The one I found would be a starting place, and hopefully it's the right one. The informant on the death cert should confirm if he's the one, but it's not always the case with informants.
At least then, it will be easier to track down the place of his actual birth, once his age has been established.
Steve.
