H2S - the round clock-like dial was where the map appeared

This week we are publishing three connected pages on the Pathfinders and H2S, starting with one about H2S itself. H2S produced a map of the ground over which the aircraft using the equipment was flying. The highly accurate navigation and target-marking which were critical to the success of the Pathfinders could not have been achieved without this radar aid. There is a fascinating and tragic backstory to its development, which will be covered later this week.