Pollock bypasses an intelligence-sharing barrier

Cunningham requested RAF Maryland reconnaissance flights, but the resulting photographs could be viewed only in a secure room and were not released to the fleet planning the raid. In David Wragg's account, Lieutenant David Pollock, a solicitor and Royal Naval Volunteer Reserve photographic interpreter, borrowed the prints covertly and had Illustrious's photographic section copy them overnight. He returned the originals so the removal went unnoticed. Lister and Boyd could then examine copies with stereoscopic lenses instead of relying on another officer's written notes. White shapes in the photographs revealed barrage balloons, whose moorings included two or three additional hanging cables. One proposed way through depended on the Swordfish's wingspan and precise alignment between the wires, although that possibility is immediately qualified as a theory. Identifying the balloons gave planners time to warn the aircrews and consider how to avoid them.