Was it Kim Jong-il? Or was it a fake North Korean leader that entertained Bill Clinton on that mission to Pyongyang to retrieve the two imprisoned American journalists?

In the absence of fact, the Hermit Kingdom has long been a free-fire zone for outlandish rumour. And they got more outlandish than ever after Mr Kim reputedly suffered a stroke in August 2008. Mr Kim was variously said to be close to death, about to be toppled by a coup, or desperately fixing the succession for his youngest son. Or was he really someone else?

The mainstay of the Kim-is-fake cottage industry is a Japanese university professor called Toshimitsu Shigemura, who once claimed that the real Mr Kim died in 2003, and that everything since has been make-believe. One Mr Kim, he maintains, even flatly confessed to a Japanese visitor, "I am a double."