We now have access to a specific mint mark original 1918 Gold Sovereign that is a special one year issue.

This coin was struck at the Bombay Mint in India for one year only, because in 1918 the German Navy were targeting boats carrying Gold from South Africa to London, so the Gold was secretly shipped to India and Sovereigns were struck to help aid the British war effort. Later that year the war was over so there was no requirement to mint circulated Gold Sovereigns there ever again.