Actually, the Bois Durci plaque in the September 14 issue is not Bois Durci. The weight at more than half a kilo gives it away. It is as the auctioneer says, bronze or more likely brass. It is a copy in metal of a Bois Durci plaque.

I don't know who made them or when but I have seen copies of several different plaques in brass and iron. They are usually fairly weakly moulded so presumably were derived from a Bois Durci plaque rather than the original dies. They use both sides of the plaque hence the "Bois Durci" wording on the back.

We have a pair of lead squeezes of Queen Victoria & Prince Albert that must have been taken from actual Bois Durci dies because they are so sharp.