The man stood in front of Vaughan, blocking his path, and asked: “Can I feel your muscles? Can I feel your biceps?”

The sheer oddness of the request threw Vaughan. He was a reserved, shy boy, and there was no-one else around to ask for help.

So when the man ordered him to flex his muscles, Vaughan did what he was told.

The man gripped each of his arms in turn. “It was sort of slimy, running his hand up and down,” Vaughan, who is now 48, recalls.

Vaughan saw a chance to get away. When a stranger passed on the other side of the road, the teenager pretended it was his father and latched on to him.

Vaughan finally arrived at the snooker hall and told a friend what had happened.

“Do you know who that was?” the friend said. The man who accosted him was notorious. He had a thing for feeling muscles. And a nickname: “It’s Purple Aki.”