Under this snow is the beech log I am currently working my way through. It is one of the nicest I have had for a while and is making beautiful bowls.
He collects offcuts from the old whetstone workings like these, see how beautiful they are.
They performed surprisingly well, I used my trusty frosts 106, I know exactly how this knife feels on stones of different grits. I cut alternately diagonally then straight with different stones and looked at the resulting grooved surface with 30x magnification to compare the results.
The first thing to note was the stones gave a lot of feel, that is they grip the knife nicely as you cut, sometimes hard fine stones can give little feedback and the knife skates on them like on glass. Second they removed metal reasonably quickly, another failing of many hard fine stones. Third they produced a good compromise polished working edge, not as fine as I normally go for woodcarving knives but a good edge very comparable to the king brand 6000. In fact the finish under magnification of the King 6000, the Shapton 5000 and the Moughton Scar stone was almost identical. A knife finished straight from this stone would be good though I went on to my 12000 Japanese natural stone and finished on the Shapton 16000. A very similar effect can be had by finishing with autosol metal polish smeared on a piece of MDF.
I can see why these stones were popular in their day. They are beautiful and work as well as the king brand 6000 grit stone. For a little stone to touch up a knife in the field I think they would take a lot of beating.
Read more about Dan's exploits here