You laugh.
I also went up in the cradles prior to taking the chopper shots and when where about 20 feet below the top a Phantom fighter shot over the dam, no higher than your Lancaster. You couldn't hear it unitl it passed over the wall, but boy you could hear it then. It seems they had been having them regularly all the time they were on the contract.
Now that I live in the Lakes I know they pass along the lakes every day.
When we were in the chopper we had one "buzz" us a bit close for comfort so I asked the pilot if he'd told the RAF we would be there. "Nope, every time I've done that they all come along and use us for target practice and I daren't move around" he said.