Johnny Johnson, one of the last remaining aircrew who flew in 617 Squadron's Dambuster raid, explained in a one-off interview with the RAF Benevolent Fund about the strict secrecy of information that was enforced by Wing Commander Guy Gibson, during the training that preceded the raid.
"There was a question of security. We were not allowed to tell anybody anything about what we were doing, what type of training we were doing or anything else," says Johnny, "nor were we told what the target was going to be."
Because Operation Chastise (the operational name assigned to the raid) critically relied on both the element of surprise and the dams of the Ruhr remaining unprotected from water-surface attacks, it was of paramount importance that no information found its way to German intelligence.
The squadron only had a two-day window in which conditions such as ample moonlight would be correct to achieve the raid successfully.
All of this meant that communications in and out of the squadron had to be absolutely watertight to avoid blowing the operation.
"All letters were censored and even the outside telephone was monitored, so there was no question of everything not being carefully looked after," says Johnny.
Johnny recalls a particular occasion when Gibson demonstrated the lengths of these security measures.
"We were having an evening meeting and Gibson really hauled a young Canadian pilot officer over the coals because he'd rung his girlfriend the night before and said: 'Sorry he couldn't make it, we've got something on.'" That was enough for Gibson. That was a breach of security and he made that stress very strongly."
This blog is dedicated to the memory of Sergeant Richard Bolitho, air gunner with 617 Squadron on the Dambusters raid, who died age 23, when the plane he was flying in hit overhead cables.