Large remaining stocks of the 1½d Sovereigns stamp from 1940 were surcharged 10d to cover the rate for the newly introduced airgraph service.

The airgraph service photographed large amounts of mail and reduced it to thumb-nail size images on reels of microfilm. These reels were then shipped saving valuable cargo space for war materials. The system also eliminated the threat of spies using microdots or invisible ink to send reports as any microdots would not be photographed with sufficient resolution to be read.

Once the reels arrived in the recipient's country they were developed and printed on lightweight photo paper about one quarter of their original size and delivered to the addressee.