An Avro Lancaster B Mark 1 (Special) of No. 617 Squadron RAF, loaded with a 22,000-lb MC deep-penetration bomb (Bomber Command executive code word 'Grand Slam'), running an engine test in its dispersal at Woodhall Spa, Lincolnshire.
Avro Lancaster B Mk I (Special) of No. 617 Squadron, loaded with a 'Grand Slam' 22,000-lb deep-penetration bomb, running up its engines at Woodhall Spa, Lincolnshire, 1944.