Even at the age of 85, John Cleese is hard at work announcing new versions of classic comedies he was involved with, then never actually making them. Remember the Fawlty Towers reboot starring Cleese and his daughter? How about the Life of Brian stage show that Cleese refused to censor even though no one had actually asked him to?

One of Cleese’s oldest ill-conceived, yet-to-be-produced reboot pitches is a proposed musical version of A Fish Called Wanda, the acclaimed 1988 comedy that he both starred in and scripted.

Cleese has been working on the Wanda musical since at least 2008, which, perhaps not coincidentally, wasn’t long after Cleese’s frenemy Eric Idle achieved Broadway success with his own musical adaptation of an old movie: Spamalot.

Regardless of whether or not it was motivated by spite, Cleese’s musical has yet to come to fruition because, according to the 85-year-old comedian, it...