 Serrate was first fitted to Beaufighter Mk . <unk> aircraft of No. 141 Squadron RAF in June 1943 . They began operations using Serrate on the night of 14 June , and by 7 September had claimed 14 German fighters shot down , for 3 losses . The squadron was later handed to No. 100 Group RAF , who handled special operations within Bomber Command including jamming and similar efforts . In spite of their successes , it was clear that the Beaufighter lacked the speed needed to catch the German aircraft , and Mosquitoes began to replace them late in 1943 . 
