[1] At the start of the Second World War, the subject of aircraft recognition had a very low priority among the British armed forces with the exception of the Army Anti-Aircraft Command.

[2] The low priority afforded to the topic was well instanced as early as 6 September 1939 when the Battle of Barking Creek, a friendly fire incident, occurred resulting in the death of a British fighter pilot and the loss of two Hawker Hurricanes.

[5] On a very limited budget the first course started at RAF Biggin Hill in February 1940 training 36 officers and men in the subject of aircraft recognition.

This method is excellent for a start, but is far too slow, laborious and meticulous to be of much use at the distance and speed at which positive identification will be vitally necessary when the real offensive begins.

It incorporated The Hearkers Club Bulletin and while remaining an independent publication received official backing when the Air Ministry and the War Office placed subscriptions for the magazine for all RAF stations and Anti-Aircraft Command units.

"Chris" Wren whose series of drawings called "Oddentification" portray aircraft with exaggerated features to emphasise the salient recognition points.

[10] As well as the armed forces and the Observer Corps there were a large number of civilian "Spotters Clubs" formed who also contributed information towards the air defence of Great Britain despite not receiving any official recognition.

[14] In each issue there was a variety of tests; regular types included "Flying photographs" - series of pictures of aircraft in flight, and "Sillographs" - solid silhouettes of (normally) threequarter views.

A regular contributor to most issues was the cartoonist Michael Cummings who continued the style of Wren's "Oddentifications" by submitting recognition tests in the form of cartoons and caricatures.