Just for the record, the crew that were flying the Valiant on that fateful day were not aware of how close they had come to death as they clambered out of the aircraft. On levelling off rather sharply when practising a " failure to pressurise in the climb " drill they heard a loud bang and decided to return gently to Gaydon. Those of us that were waiting at the dispersal could see that the aircraft was making like a naval version with one wing ready to fold up. One very lucky crew and the end of my Valiant captains course'