6 Pence - Charles I 1st milled Briot's issue

Nicholas Briot, a French-born die-sinker who had worked at the Paris Mint, came to England in 1625 after years of frustration trying to introduce screw-press minting to France. He finally got his opportunity at the Tower Mint in 1631, producing a short run of mechanically struck coinage that was technically superior to the hammered currency it was meant to replace. The milled pieces were too expensive to produce at scale and the experiment was suspended after roughly a year, making this issue genuinely short-lived rather than nominally so.

Briot subsequently moved to the Edinburgh Mint in 1635, where he had better institutional support for his methods.