Who Do You Think You Were? Channel 4

“Do you realise what you’re letting yourself in for?” is surely the worst thing to say to someone in order to put them at their ease, especially when they are about to step into the subconscious unknown. But down-to-earth fireman Neil Clarke took these words from hypnotist Trevor Roberts in his stride. His main concern - if it turned out he had lived a previous life - was that he was “a nice bloke and not some sort of murderer”. But no, this wasn’t a Mitchell and Webb sketch.

It was the opening scene of a serious documentary on past-life regression. However, as this half-hour journey into the twilight zone of suburban Shropshire progressed, it did seem to have more in common with the former than the latter. You can guess what came next, can’t you? Partly because Clarke had already joked about being a murderer, but more pertinently because one of the most telling things about past-life regressions seems to be that people were always Roman centurions or Battle of Britain Spitfire pilots: they are never just some underling who looked after the horses. So having already unnerved our friendly fireman with his botched bedside manner, Roberts took poor Mr Clarke "back through time and space" to what unfortunately turned out to be the funeral of his past-life wife.

It’s a big pile of shit: a metaphor for this documentary

As the previously chipper Mr Clarke began to sleepily mumble about his miserable 19th-century existence, my inclination to channel-hop to something less silly gradually subsided. With his eyes shut and mind apparently two centuries away, Clarke told Roberts he was a wealthy landowner called Peter John Hawksworth who lived in Glossop. But he was angry and lonely because he lost his wife and then all his money, before finally being sent to prison for murdering a debt collector. We then saw Clarke and his equally grounded 21st-century wife watch the footage of Clarke’s session and try to come to terms with its implications and unquestionable weirdness.

“It felt like something that couldn’t just be made up", said Mrs C, "and certainly not by my husband who I’ve known for 13 years.” Clarke and his wife then set out on an investigation based on the “facts” they had at their disposal. This included a visit to an agreeably open-minded genealogist and a journey to a farm in Glossop which Clarke confessed didn’t look in the slightest bit familiar.

But despite its opportunity for haunted-house hyperbole, this slice of supernatural “reality” TV from director Pinny Grylis was a fairly muted affair. There were no night-vision cameras shakily combing dank cellars, or histrionic voiceovers trying to fan non-existent flames of fear. Partly because of this restraint, and partly because I felt my leg wasn’t intentionally being pulled by either the hypnotist or his patient, it was actually fairly engrossing. The hypnotist was admirably open-minded about less far-fetched explanations for what he does, such as the notion of inherited memories or perhaps the even more credible explanation that his clients are mentally excavating memories of a book they read years earlier but had since forgotten. And Clarke himself was undoubtedly sincere in the reports he gave of his experience, and impassioned and rational in his quest for their meaning.

The last time we saw Clarke he was walking past a hillock of manure on the farm that it’s very unlikely he ever owned. Smiling, he half turned to camera and said: “It’s a big pile of shit: a metaphor for this documentary.” I laughed out loud. It’s not often that someone in the programme one is reviewing delivers their own dismissive critique just before the credits roll: very Mitchell and Webb. The bruised and understandably embarrassed Mr Clarke was being a little harsh. Who Do You Think You Were? didn’t offer much in the way of analysis but it did hold the attention. In fact there’s probably a series in there somewhere: perhaps a prize could be given to the punter who has the dullest (and therefore most credible) past life.