It was common in the late 19th and early 20th Century for packets of cigarettes to include trading cards. Usually issued in sets of 25 or 50, cigarette cards had the dual purpose of stiffening the packaging and advertising cigarette brands. They also presumably increased sales of a brand if it issued cards which were particularly desired.
In the 1930s Royal Mail and the cigarette company W.H. & J. Woods Ltd joined forces to issue a set called Romance of the Royal Mail which depicted aspects of postal history up to the early 20th Century. Amongst the cards are some well-known stories including how John Palmer established the first regular mail coach services and the introduction of the postcard.
Less familiar is a card depicting mail deliveries to the South Pacific island of Tonga. The card explains:
As the nature of the coast of the Tonga Islands make landing difficult, the mails are delivered by the simple method of sealing them in old tea and petrol tins and throwing them into the Pacific, where they are collected by a native who swims out from the shore. The far-flung organisation of modern communications ensures dependable deliveries in remote corners of the world, where the arrival of the post is an exciting event, just as it does in the city street where the postman is seen three or four times a day.
Visit Flickr to see all of the Romance of the Royal Mail cigarette cards.