TV review: The Da Vinci Shroud

FIVE'S Revealed series specialises in the arcane minor conspiracy theory, asking questions that promise dramatic new information and spending 50 minutes tantalisingly hinting at revolutionary theories. But it nearly always peters out limply, with a final ten minutes having to admit that the evidence doesn't stack up. Was Dr Crippen innocent? Did a Victorian tabloid editor make up Jack the Ripper? Are crystal skulls space computers for aliens? The answer is invariably "no, not really" and you feel like you've wasted an hour.

Yet, for once, the series had a reasonably strong case to make with The Da Vinci Shroud: Revealed which, as the title suggests, argued that while it now seems that the famous Turin Shroud cloth image of 'Jesus' is a medieval forgery – carbon dating tests having established its age to the point where even Pope John Paul II shrugged that he would leave it up to scientists to decide – the forger was, of all people, the equally famous Leonardo.

This initially sounded like wishful thinking, like those people who say they've been regressed to a past life and always claim that they were Cleopatra or Napoleon, never Ulric the local blacksmith. In his undoubtedly busy life, how could Da Vinci have had time to fake a religious icon in between quite a lot of painting, inventing the helicopter, telling jokes to Mona Lisa, being an icon of gays and left-handers, leaving rubbish clues for Tom Hanks, and son on? And, given the immense interest in him from his lifetime onwards, is it really likely that no-one would have made the connection before now?

Yet it wasn't just that computer mapping shows the image said to be Jesus has the same dimensions as a self-portrait of Leonardo (after all, a lot of faces are similarly proportioned), but the actual technical challenge of creating such a clear negative image on linen could only have been done by very few people. The forger would have had to be in the right place, with knowledge of both anatomy and art, as well as a technical imagination which could have conceived of a form of photography, in effect, centuries before it was actually invented. The attribution suddenly began to seem much less coincidental.

Until … ah. They got me again, didn't they? After all that evidence, it turned out that there's a medallion showing the shroud a century before Da Vinci was born. This is the Revealed way, hiding rather crucially important details until late on so that those new to the subject are carried along blithely only to be brought suddenly down. By that time, you've invested almost an hour in the theory, so you might even look around for loopholes – perhaps Da Vinci made a copy of an earlier shroud? Perhaps, er, he was a lot older than he looked? Could alien crystal skulls have been involved?

It's a cheat's way of making historical documentaries, with standards of proof which would be laughed out of court or academia. Yet these programmes don't actually lie; perhaps the sensational revelations promised draw in gullible viewers but they do at least get a fair amount of information about the subjects in order to make up their own mind. And, well, they are on Five: don't expect BBC4 levels of intellectual rigour, because it's not going to happen. Still, it was disappointing to have been temporarily taken in. Next time I'll take advice from the theme tune to Five's other most implausible show, CSI Miami: I won't get fooled again.

TV review: The Da Vinci Shroud – Revealed