Inspired by a story his father related to him, Evan Harris a Bangor Uni student, ascended Snowdon, Wales’ highest mountain, and spent an afternoon launching paper planes from the summit and watching them fly all the way down to the road running through the Pass of Llanberis.

This gave him an idea - a tourist souvenir post service - based on the paper planes. Stamps would be printed and template paper-plane sheets and sold. If you followed the instructions carefully your plane would descend some 2,000 feet, to be collected up and forwarded to the addressee by Royal Mail. There were three stamps, one for each year the service ran, plus one rarer example which was withdrawn soon after issue. The stamps were illustrated by watercolours painted by Evans’ father. Different paper plane designs were also available. It was popular enough to provide the students involved in beer and curries throughout their university years.