Thanks eightbore for the contribution of effort to the cause. Do you recall any listing for German makers like Abesser(Paul) & Merkel(Ernst)? They appear to have been in business in the 1920s and early 1930s and had Sloan's listed as being "sole agents". One Abesser & Merkel drilling I've seen had ejectors on all tubes. Ernest Merkel attained the rank of master on August 14th, 1929. Speculation is that he was from the line of Friedrich Ernst Ferdinand Merkel. Paul Abesser must have been a master in order to found the firm.

Kind Regards,

Raimey
rse