A specially adapted Lancaster bomber - Type 464 (Provisioning), a special B III - carrying an Upkeep depth charge for use against German dams. This was the Barnes Wallis-designed weapon that the RAF’s 617 “Dambusters” Squadron used against the Ruhr dams during World War II. This Flight Artworks image features Lancaster ED932/G, coded AJ-G, as flown by the leader of the operation, Wing Commander Guy Gibson, in May 1943.

The most obvious adaptation to accommodate the secret weapon was the cutting away of the bomb bay on these aircraft. Also very noticeable: the removal of the mid-upper gun turret to save weight. More subtly, the aircraft had a more bulbous style of bomb aimer's blister, later fitted to all Lancasters. And they were fitted with downward-pointing spotlights, offset to starboard, to gauge a 60ft altitude over water.