2025 Britannia Silver Proof 1 oz Coin UK. 999 Box & COA Mintage Of Only 4500! Limited edition presentation of 4,500 coins. Contains 1 oz of. Comes in the original mint box. Obverse: Features the effigy of His Majesty King Charles III and the monetary denomination, designed by Martin Jennings. Reverse: Depicts a unique design of Britannia by Bradley Morgan Johnson, exploring Britannia’s connection to the sea. She stands boldly with her staff and shield over the ocean. Sovereign coin backed by British government. This Britannia silver proof coin would be a great addition to any coin collection. Mintage: Only 4,500! Reverse Designer: Bradley Morgan Johnson. Obverse Designer: Martin Jennings.