Can I ask where you found the image of that headstone? That may well be them as I am aware that John William Lowers and Hester named there first Son John William which is where things get a bit complicated. I know Hester is Buried in Plumstead Cemetary in 1918 but up to this point I'd found nothing on John William or his Son. So it seems possible they may have moved across the country to Durham. Hester and Johns other Sons ended up in the Merchant Navy which is how they came across to the Uk.
If anyone is based in SA at all ( i'm not sure how the archives work out there) but if you ever get a chance to have a look for any records mentioning a John William Lowers, Hester Lowers, Arthur Lowers, Edward Lowers or James Lowers I would love to see them. Real Shame I can't seem to follow anything more based on John Williams military Service.Do you think I'm right in thinking he had Served recently and to extent as an NCO with Rank due to his appointment as RQMS for the WPMR?