Yes, even over in Perth in the early-to-mid 70s, Colin could be Absolutely Bloody Brilliant OR pretty darn awful, depending on what he'd taken - must've been rather difficult for the MCs!!
But you Always wanted to listen to him, in case you just heard THE song or bracket of your lifetime!!   His "Davey Lowston" was, for me, just one such example of those latter times.

Sure hope he has reincarnated into more singing/playing lives!!
Cheers!
R-J