A Lancaster with radial engines - Bristol Hercules. To guard against the possibility of shortages of RR Merlins, the Lancaster was adapted to take the Bristol engine. This is the prototype, built at Chadderton and assembled and first flown from Ringway on 26 November 1941. 300 production aircraft were built by Armstrong Whitworth and served with six Bomber Command squadrons. From Avro 60 years ago.