Henry Fear maker

[Huw Eastwood]

We'd always assumed the bolt was swapped from a lock that had 9 slides as it seemed the most logical explanation- it has both original keys and the detector mechanism in the cap.
It's also a common size with roughly an inch and an eighth cylinder and a 4 inch backplate.

I'd love to see 18 sliders in a cylinder this size, i'd always assumed that was the domain of the much bigger powderproof bankers versions.

[Huw Eastwood]

So the Cotterill-Wilson locks were specifically the first of the two different ACME designs (lever locks with half moon keys with stepped grooves), and not the original Royal Climax patent (radial slides) design.
My lock now makes about as much sense as the patent markings on this one!!