Whilst out walking today, I found several of these ‘war grade’ bottle necks and screw-in stoppers. They were on the edge of a ploughed field alongside a public footpath.
What does ‘war grade’ refer to? To glass? The stopper, or the contents. I’ve been hammering Google to try to find out.
Sadly, I haven’t come up with much. The stopper is probably made from some sort of recycled plastic due to shortages of other materials during WWII.