Obverse: Britannia seated (R), a trident and shield at her side, clasping the hand of a naval boy, the muzzle of a cannon at his feet; the stern of a vessel with Union Jack (L) a ship in the distance (R). Legend: "MARINE SOCIETY INSTITUTED MDCCLVI" Exergue: "INCORPORATED MDCCLXXII". Reverse: inscription within a floral wreath. "REWARD OF MERIT TO (incuse) WALTER J. DIGGINS". Fitted with a bar and dark blue ribbon.

The medals were presented to former Warspite boys for five years of exemplary service after they had left the ship and joined the Merchant Navy. They are now awarded annually for deeds of exceptional merit at sea.