Malcolm,

Just a minor correction. The drawing number is AB694 which may well identify the specific type (although bear in mind some drawing numbers were for several different types). Unfortunately, I don’t have access to my list until tomorrow, but someone else may be able to confirm.

The number you mentioned is actually the diameter, ie the overall length of the propeller – it shoudl be 3.350 metres which certainly makes it big! The P number refers to the angle of pitch of the blades.

Don’t worry – I know it is VERY sad that I know these things. That said, it is surprising how often such information comes in useful and being one of the few people in the entire country with such knowledge does keep me in demand.

Tangmere1940, I’m afraid the IWM photo looking up the transmitter tower is most definitely NOT Poling. The general view of the station (IWM neg no CH 15173), the vertical aerial and the private shot are, but the view up the tower is not. How do I know? It’s the wrong type of tower, and quite distinctive if you know the three different designs which were used. This photo is almost certainly of a tower at Bawdsey in Suffolk.

Hornet Moths would have been used in the same way as Blenheims were – they would fly towards a radar station at a set height and bearing and the coverage of the radar would be determined as a result, producing what were known as vertical polar diagrams (basically a drawing showing the areas in which the radar station would detect an aircraft). They would also fly away from the radar station, again at a pre-determined height and bearing, and plotted until they disappeared. This was the process of calibration which the aircraft from the Radio Servicing Sections, later Signals Wings Calibration Flights and eventually the Calibration Squadrons, carried out.