Where is the mint mark on an English Halfpenny?

If a British Halfpenny has a Mintmark at all, it will be a small "H" on the reverse, near the year, indicating that is was struck by Ralph Heaton & Sons, Birmingham. All British decimal Halfpennies were minted at the Royal Mint Llantrisant, South Wales. Prior to that, the Royal Mint at Tower Hill produced most British Halfpennies from about 1810.