I am reminded of a terrific folk bash at the Bishop Grosseteste college, Lincoln (UK), 30-odd years ago. Donovan was to have headed the bill but pulled out and fobbed us off with a Scottish duo called the Humblebums, who no-one had heard of, but who Donovan assured us were sensational. He was right. At one point they took a break and handed over to a softly voiced lass, and the volume of audience chatter increased. One of the Humblebums - only 20-ish, but bursting with charisma - jumped back on stage, said "excuse me, lassie," took the mike off her, and bellowed: "If you want to talk, leave. NOW. If you want to stay, don't be SO FUCKING RUDE!" Instant silence, and the mike was handed back. The humble bum in question became better known as Billy Connolly; the other was his pal Tom Harvey.

I also remember some punter heckling the Dubliners at the Albert Hall for refusing to sing rebel songs. Eventually Ronnie Drew said: "Let's have a spotlight on that fella, so we can see if the rest of him's as big as his mouth." Evidently satisfied by what he saw, he said to the bloke: "If you want to carry on this argument, we'll both go outside now, and leave everyone else to enjoy themselves." The challenge was not taken up, and there were no further interruptions.

One last thought. In 1956 Kuruschev denounced Stalin at a private sesion of the Moscow Soviet. According to Rene Cutforth, a Daily Express journo who wangled his way in, someone shouted: "If you knew he was doing all this, why didn't you stop him?" Kruschev shouted: "Who said that?" And when no-one spoke up, he said "There's your answer, my friend."