 Early development was prompted by a 1936 memo of Henry Tizard on the topic of night fighting . The memo was sent to Robert Watt , director of the radar research efforts , who agreed to allow physicist Edward George " Taffy " Bowen to form a team to study the problem of air interception . The team had a test bed system in flights later that year , but progress was delayed for four years by emergency relocations , three abandoned production designs , and Bowen 's increasingly adversarial relationship with Watt 's replacement , Albert Percival Rowe . Ultimately , Bowen was forced from the team just as the system was finally maturing . 
