On Noel Murphy's album 'Caught in the Act', the track in question is labelled THE BOXER (THE FOLKER),and is simply credited to (Simon).

There is another parody on the album of 'I WALK THE LINE (I PULL THE TWINE). Don't know if he was responsible for the words on this one, but again it is credited to the original writer (Cash).

So, your guess is as good as mine - maybe better!

Rog

P.S. I remember Bert Weedon as being somewhat more than moderately popular! I believe he is still alive.