Hard to see from the photo but the cutting action may be similar to that of those excellent chatter-free countersinks where the cutting edge is formed by the convergence of a hole at 45 deg to the tool's axis with the 90 deg, etc cone.

Did you check subsequent ME Postbags to see if anyone wrote in about it?

I expect the stock would be turned by a drill or brace and introduced into the bore of the tool to cut. The tool was likely intended to be held in a vise.

A neat idea, but tool life would likely be short cutting steel, brass probably would enable a long tool life. Not easy to resharpen the cutting edges I think, if the tool were hardened.

ega

I had a look at the "Postbag" and "Readers' Queries" in some later editions while digesting my tea, but there was no mention of the device.

Then I got bogged down in reading some of the letters. Its amazing how rude they were to each other in those days!

Have you ever made a 'spot face cutter'? Essentially a bit of silver steel, hole bored axially, saw across the end twice then file 4 angled lands on the end, insert an alignment dowel in the hole. If you leave out the dowel and spin it into some wood you have a 'plug cutter'. Well this si just a two land version for metal.

Google spot face cutter and plug cutter images if necessary.

Probably a good idea for non lathe owning model railway boys of the time who could make the gizmo in the school workshop.