Air Defence of Great Britain: Instructions for observer posts 1938

At the start of the Second World War the UK had a highly developed air defence network which was dependent on information gathering and dissemination. Providing commanders with timely intelligence with which to make decisions and deploy their forces accordingly.

The Observer Corps was an integral part of the system. Radar was still in its infancy and was only able to detect aircraft flying at medium to high level over sea, once over land the aircraft could not be tracked by radar and a network of observer posts, manned largely by volunteers tracked enemy raids over land. At the outbreak of war there were approximately 1,000 Observer Posts and 30,000 observers. The information that was gathered at an Observer Post was sent to an Observer Centre where it was plotted and added to information received from other nearby Observer Posts. The compiled air picture was then passed to Fighter Command HQ , Group and Sector HQs providing commanders with as much available information to support effective decision-making. This pamphlet describes how an Observer Post was to be maintained and run.