As I approached, he was playing away on his guitar, bluesy rock, good, but nothing that particularly grabbed my attention. I wasn't quite as far along the corridor as the pitch when suddenly he stopped playing and walked purposefully along with the flow of the crowd ahead of me, calling out to someone, trying to get them to stop.
It was important enough to the busker that the person he was trying to track down was failing to be connected to until we were all around the corner and halfway down the stairs from where the guitar case, full of donated coins, had been left. The busker's side of the conversation was the only audible side, but he had in his hand an open wallet, full of cards. "It has your ID in it.", he said, taking a couple of tries to successfully hand back to the wallet to the slightly glassy-eyed man who must've tossed it into his case.
The busker asked several times if the guy was okay. The guy seemed vague but nodded. And then the busker said that once, someone else had thrown their wallet, with cards, into his case, and then had gone and thrown themselves under a train.
No wonder it meant so very much for him to track down the next person who'd done it! Buskers, or at least one of them: trying to save lives one wallet at a time.