Some of the most stunning stamps are the simplest, and here is a case in point.

It takes the classic image of a gas flame, very well known to millions of homes in the late 1970s, and places it on the calm surface of a stylised North Sea. Beneath the surface lie the strata of sediment which contain the crude oil from which the gas will be refined. 

The various hues of blue within the pearl of the flame are reflected in the sea and sky, perhaps (as much of the gas comes from Scottish waters) subliminally suggesting the Saltire? They are then contrasted with the less attractive submarine tones, reminding us that the power has first to be extracted from the depths of the sea bed.

Design: Peter Murdoch.

Printing: photogravure by Harrisons.