During the English Civil War, most coins minted by Charles I at his various provincial wartime mints carry the feathers. The feathers appear on these coins because Charles I had no access to the Royal Mint in London and instead transferred the Aberystwyth Mint (originally established to coin Welsh silver) to Shrewsbury and then Oxford as an emergency measure. All the Civil War provincial mints are therefore in effect sub-branches of the Aberystwyth mint.
