It's identical to the one I have in my bay, only 1/2 the size, same mechanism and lever etc. Looks very much like it might fit a splittie. Unfortunately I don't know the origins of mine, I picked it up at Bugfreeze almost 20 years ago, always assumed it was the same as could be optioned on the Devons and as such probably of British manufacture?
The Westie ones appear to have a more refined operating mechanism... https://nlavw.com/2443-thickbox_default/westfalia-aluminium-mosquito-net.jpg
As a Devon owner, I have to say it's quite typical, they attempt to imitate Westfalia but only succeed in simplifying and cheapening
I prefer the Devon windows to the rattly Westfalia ones with the silly knob that takes 20 spins ... if the weedy splines haven't been mangled. You can adjust then very easily by loosening the screws and sliding the handles up or down. Ker-klunk and locked shut, so quick and easy.
You may be right, must admit I've never had the opportunity to play with a Westie one, they do look nicer though (in my opinion). Having said that, in 20 years I've never had any bother from my Devon window, no rattles etc and as you say, can't beat the instant convenience of click open - klunk shut.