The last of the Polish bomber squadrons, 305 Squadron was formed at RAF Bramcote, Warwickshire on 29 August 1940. It was initially equipped with the somewhat obsolete Fairey Battle aircraft, but was requipped in November 1940 with twin-engine Vickers Wellington heavy bombers. The unit began operational flying in April 1941. Between June 1941 and August 1943 the Squadron was based at RAF Hemswell, Lincolnshire.
In August 1943, the Squadron was moved to RAF Swanton Morley and thereafter ceased its affiliation with RAF Bomber Command; Instead, it was absorbed into the freshly formed Second Tactical Air Force, a specialized arm of the RAF that was centred on tactical air strikes of vital enemy targets (such as bridges, supply trains, etc.) on the Continent.
During this period, 305 Squadron converted briefly to North American Mitchell medium bombers before adopting the De Havilland Mosquito FB-VI, the aircraft that the Squadron operated for the remainder of the European campaign. Through 1944, the 305 was stationed at RAF Lasham in England and then briefly at RAF Hartford Bridge before moving to the Epinoy airfield in France in November 1944. After the hostilities ended, the Squadron continued to operate in Germany as part of the occupation forces and, after a brief return to England, was finally disbanded on 6 January 1947.