Edward abdicated 11th December 1936, so it would have been known then that Albert as Duke of York and heir presumptive would then be king, and that the coronation would take place some months later in 1937. George VI's coronation date of 12th May 1937 was the date that had been planned for Edwards coronation. Hence the medal would have been made in December 1936, with the appropriate hallmark, showing 1937 coronation date.