THE DEVELOPMENT AND MISDIRECTION OF BRITISH NIGHT AIR DEFENCE: 1940-1943

By 1939 the RAF had established an aerial command and control system integrated into a nationwide radar network, which was unsuitable for use at night. The technical complexities of night air defence greatly exceeded those of daylight operations, with a prototype airborne radar in development, but by the time the Blitz started night defence rested on six squadrons of underpowered Blenheims equipped with experimental and unreliable radar. Fighter Command was forced to introduce unproven equipment and aircraft unsystematically, with training and tactics developed concurrently. A shortage of aircraft and aircrew limited operations and led to the Luftwaffe being practically unopposed during the winter of 1940.  Significant results for night fighter defence only began after aircraft, GCI and AI radar had been optimised into an integrated weapon system in early 1941. Demonstrating a sense of desperation, the disappointing initial performance of AI, lack of understanding by senior officers and political pressure prompted Fighter Command to employ Hurricanes in the night fighter role (‘Cat’s Eye’ fighters), and then less conventional means of air defence such as the 'Long Aerial Mine' ('Mutton') both of which diverted aircraft and crews trained for night interception away from such duties without anything significant being achieved. From July 1941 Fighter Command began to receive experimental 'Turbinlite' Havocs fitted with Helmore searchlights in place of armament, but these was not used in action until the Baedeker raids in April 1942, with a singular lack of success. Despite poor results, Fighter Command persisted with operations until late in the year, when a proposal to abolish ‘Turbinlite’ was made. The introduction of centimetric radar had confirmed the superiority of the AI/GCI method, and ‘Turbinlite’ was finally abolished at the end of 1942, with the Mosquito supplanting the Beaufighter as the principal night fighter, and centimetric AI prevalent by 1943.

RAF Museum Battle of Britain Lecture: The Development and Misdirection of British Night Air Defence, 1940-1943