Low Level Bombsight, Mark III use in October 1942. Coastal Command had priority on deliveries and only small numbers reached Bomber Command. The first examples arrived in May 1943 and were fit to Douglas Boston bombers of 2 Group. In 1944 the sight was trialled on the Avro Lancasters of No. 617 Squadron RAF, the Dambusters, who carried out a single low-level attack with them in late 1944. Most examples sent to Bomber Command equipped a small number of De Havilland Mosquito aircraft in No. 627 Squadron RAF (who normally operated as pathfinders) and No. 8 Group RAF (Pathfinder Force). The sight remained with Coastal
No. 421 (Reconnaissance) Flight RAF were issued to 421 Flight and the Hurricanes went to other squadrons. No. 421 (Reconnaissance) Flight RAF No. 421 (Reconnaissance) Flight was a specialist RAF fighter flight created on 21 September 1940 to patrol the Channel and provide early warning of the types of incoming Luftwaffe raids from occupied France. It was later expanded to full squadron strength and renumbered as No. 91 Squadron on 11 January 1941. Its role led to its pilots being nicknamed "Jim Crows". In late September 1940, Air Chief Marshal Hugh Dowding was faced with two problems. The first was a change in Luftwaffe tactics.