The Mystery of Rennes-le-Château is beautifully filmed, but that’s largely a consequence of its subject matter. Beyond that, it falls into just about every R-l-C trap there is. Although writer and presenter Stewart Ferris claims to be examining the various theories, he trots them out as fact. Saunière found the now-familiar coded documents in the church: fact. Saunière had an affair with singer Emma Calvé: fact. “When the Knights Templar were rounded up and executed in the 13th century, the only members to escape capture were those based near Rennes-le-Château”: fact. What?

Ferris interviews author Graham Simmons, “who knows more than anyone else here about the mystery of Rennes-le-Château” – to which Simmons modestly replies: “I think that’s probably true”. Simmons trots out the line that the Knights Templar dug in Jerusalem and found something which directed their search to Rennes. He also says he’s about to reveal proof that “Mary Magdalene is buried in a Templar tomb beneath Rennes-le-Château together with documents and objects that would prove her identity”. Unfortunately, Simmons died without revealing where the Magdalene’s tomb is.

Surprisingly, and quite delightfully, the one voice of reason in the entire DVD is Henry Lincoln, who started the whole R-l-C/Saunière/etc. mystery off (at least in English) back in the 1970s. Could the Ark of the Covenant be buried at Arques? Lincoln laughs. “Not as far as I know. If you wish to believe these things, hurray.” Could Jesus be buried under Mount Cardou? “What a load of hysterical rubbish! That’s farcical!” And utterly exasperated, in response to a particularly daft theory from Stewart Ferris: “Oh, I don’t know. Who knows? It’s lunacy.”

But this DVD is a model of common sense in comparison with The Secret Island of the Holy Grail, a cobbling together of the most credulous approach to the Grail, the Templars, the Priory of Sion et al, with speculations based on the flimsiest of evidence supposedly found in churches on Hayling Island near Portsmouth.

Example: the Knights Templar were founded with their “real objective to concentrate on the recovery of the remaining Temple treasure”. Example: the Priory of Sion “is still active politically after almost 800 years”. Example: the Albigensian Crusade “gave a long-sought-after opportunity to search for the legendary treasure of the Visigoths and the Knights Templar, but nothing was ever found in any of the Cathar castles as one by one they fell to the invading army.”

Does anything further need to be said?

“Perhaps,” says presenter Wendy Adams Evans near the end, “we’ve already done enough to highlight Hayling’s claim to be the secret island of the Holy Grail.” Nope. They’ve done nothing to highlight that claim, beyond making one assertion after another with zero evidence for any of them.

Incidentally, now that everyone and their maiden aunt is producing DVD documentaries, you really come to realise the importance of professional skills. These two, especially Secret Island, suffer from poor sound balance between studio and location, wind noise on microphones, and a lot of distortion. Regrettably, it also becomes evident why “proper” documentaries are usually presented by experienced actors.