Sydney Carter wrote a few funnies - for example "Down Below"

The incompatrable "Cosmotheka" didn't write any songs that I'm aware of, but they brought some crackers back to light.

And don't forget their mates Chaz'n Dave (far more famous, though not in the same league - but pretty good). Here is a rather charming video of their Rabbit (Which come to think of it is very reminscent of Jake Thackray's "On agioan,on again,on again"... Thematically, I mean.