I know its claimed on many sites to be sung by Billy Connolly. I think the reason why you find it hard to find on his site is that its not Billy singing it. I've listened to it many times and as far as I'm concerned it's just not his voice.

I've only ever been lucky enough to see him live once, around 25 years ago and had to translate for the current girlfriend right through his act.

He has a great way with hecklers "I don't suppose your mouth bleeds every 28 days" being the one I remember.

Al