Several years ago, the author acquired an octagonal punch suspected to have been used by counterfeiters to create countermarked dollars similar to the official Bank of England issues of 1804. The punch was tested on soft metals and a genuine dollar. Close inspection revealed a very small, and previously un-noticed, mark in the folds of the drapery. This mark is not present on the Maundy penny bust. Inspection of several genuine octagonal countermarked dollars reveals this mark to be present and suggests that this is an official punch.
A Punch for the Octagonal Countermark of 1804 – Gary Oddie
BNS Research Blog 