I think it's Major Clanger speaking. Obviously this is a translation from the original Clanger language that we only hear as whistles

@Sarahw

You know about the actual (mild) swearing in the real Clanger episode?

@suearcher
No! Do you speak Clanger Sue?

@Sarahw

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.

@Sarahw

Years later, when the Clanger toys came out, the ones you squeeze and they make Clanger sounds, a simple sample was needed. And so of course, Postgate made sure it was "Oh, sod it, the bloody thing's stuck again!" that was used....