I agree it completely fits in with the “Yes, Minister” thing, but I have a notion at the back of my mind that it could also have originated in “Punch” or “Private” Eye. And I think they just called it irregular verbs. Any other U.K. people seem to recall that? Little column towards the back of whichever magazine it was?
Ack, pardon me, this is turning into stream of thought stuff, but I NOW know that what I have in mind there was the same irregular verb game but done in Franglais, so they might have been ripping it off from “Yes Minister”. Hmmm.
Still, I’m going for the "appeared in magazine and was simply called “irregular verbs” idea.
(And here’s a problem, a bijou little problemette. You evil people have forced me just now to go and pick up my copy of “The Complete 'Yes Minister” and I might just feel a need to read through the whole thing. AND I even braved a tiny little spider to find it!)