Trafford Park was largely turned over to the production of war materiel during the Second World War, such as the Avro Manchester and Avro Lancaster heavy bombers, and the Rolls-Royce Merlin engines used to power the Spitfire, Hurricane, Mosquito and the Lancaster. The engines were made by Ford, under licence. The 17,316 workers employed in Ford's purpose-built factory had produced 34,000 engines by the war's end. The facility was designed in two separate sections to minimise the impact of bomb damage on production. The wood-working factory of F. Hills & Sons built more than 800 Percival Proctor aircraft for the RAF between 1940 and 1945, which were flight tested at the nearby Barton Aerodrome. Other companies produced gun bearings, steel tracks for Churchill tanks, munitions, Bailey bridges, and much else. ICI built and operated the first facility in the UK able to produce penicillin in quantity.