Crowned head of King George VI facing left; around, the legend GEORGIVS VI D · G · BRITT · OMN · REX F · D · IND · IMP: (George VI, by the Grace of God, King of all the Britains, Defender of the Faith, Emperor of India); below the neck truncation in small letters the artist's initials, PM (for Percy Metcalfe).
At centre, dividing the date 1940, a palm tree; around outside a circle broken by decorative extensions adjacent to the date, BRITISH WEST AFRICA (above) and the denomination ONE SHILLING (below).
All shilling coins for the year were minted at the Royal Mint and thus have no mint mark. However, traces of a mint mark could be visible on some examples. As Remick explains - the mint mark for the Heaton Mint was not always properly removed from the die (which was always prepared by the Royal Mint before use by the other mints, and the master punch had a mint mark which was normally obliterated before it was used by the Royal Mint).
Remick lists such "ghost marks" as defects appearing as 1939-H, 1939-KN, 1939-KHN, 1940-H, 1942-KN and 1946-H shillings. "KHN" is most notable, as it means ghosts of two mint marks exist at the same time.