You know about the actual (mild) swearing in the real Clanger episode?
Well, I've read about it...
Oliver Postgate and Peter Firmin wrote proper scripts for each episode, and then played swannee whistles to the rhythm of the words. In one episode, the dustbin lid of a crater sticks, and the script actually had Major Clanger saying "Oh, sod it, the bloody thing's stuck again"
BBC bosses were not happy when they saw the script, but Postgate reasoned that nice minded children would probably hear "oh bother, the blooming thing's stuck again" and it stayed.