Rare MARPLES Mortice Gauge. (37617)

I don’t find any reference to this model in any of the catalogues I have access to. Clearly stamped “MARPLES” on the head stock next to the nasty cut mark? What’s most unusual is the knurled thumb adjustment that moves so nicely with two sharp pins, nice brass stem that the only other models I see have the screwdriver nut adjustment.

Price is inclusive of postage to mainland U.K.