Rats, I was forced to go looking for my Olympus XA 2.
Not a rangefinder but I did realy like it in the late 70's and I've still got it somewhere.
But that means I've got a second hidden camera stash ... ooooh
Went looking and I haven't found it yet, but I did find something made in Sept 1960:

My Avometer from GEC Hirst Research Centre (my first job)
I may have to get it working again