Sailaway's mention of a torch, and my "Oh duh!" recollection that I have a torch bottle to worry about as well, makes me wonder why no one sells a simple positive brass cap to screw onto the bottle as a security fitting?
Just a piece of (non-sparking!) bronze or brass rod, with the 1" female threads tapped into it, and a rubber sheet inside, so it could be screwed onto a gas bottle as a (reusable) "gas tight" cap. The same way that Schraeder valves use caps, and AC fill ports use caps, to make sure the valve isn't leaking.
Nice cottage industry for someone with a lathe...