Vklim - thank you! From the attitude of the lizard (the curve that it is holding its body in) and the presence of the crown, it seems far more than coincidental. The date seems late for this type of thing. Knowing the headstmap on the 7.9 cartridge in the device in question, if in truth it is a real cartridge, would be interesting.
Either a British ship of war or a base would certainly have a machine shop well up to making this sort of thing, either as an official symbol or souvenir of some sort, or by some individual(s) as a “midnight project.”
If the cartridge is a Besa round, or a date from any belligerant in WWII, I would say that you found its source. If a WWI round, it is still possible, but would probably need more research, if any such research is possible.
this is precisely why I toss into the hat some of these comments. Sometimes one just needs a starting point. I don’t know enough about computers or even foreign militaria to have found this on the web, like Vlim did. I tried to find something before writing my question, but to no avail. More skilled hands did the job. Now it will be fun to see if this pans out.
That lizard on the H.M.S. Lizard’s Crest sure looks like the one in the device!