I recently found a mention of Otway in the autobiography - "Bob Harris - The Whispering Years". The passage goes as follows, and the errors are his, not mine -
"But the feeling of things spinning out of control was further enhanced by an extraordinarily chaotic live studio performance by Wild Willie Barrett and John Ottway of their current hit "Cor Baby, I'm Really free". Constantly out of camera shot, smashing and trashing his way through the set, Ottway ended the number by throwing himself off the top of a 10-foot speaker stack into the equipment below, almost knocking himself unconscious. I just couldn't work out what to make of it. Yes, it was funny, but all rather sad in a way."