As is normal with such things, The Blair Witch Project is much less original than its fans would like to believe. For example, The Last Broadcast predated it and bears more than a slight resemblance – but even before that, back on Halloween Night 1992, the BBC came up with its own pseudo-documentary ancestor: Ghostwatch. This drama was only screened once, and is most unlikely to be repeated: it caused near-panic at the time, and a lot of people believed it to be entirely real, for several reasons. Although the announcement beforehand clearly said it was a drama, if you tuned in later, there was no obvious sign. Many of the cast were people better known for factual TV than plays or movies. [The main exception was Red Dwarf’s Craig Charles] And Steven Volk’s screenplay was more restrained and plausible than you might expect from the man who did Gothic: noted paranormal author and researcher Guy Lyon Playfair was a consultant, and his input lent it much authenticity.

Its plot is devastatingly simple. The BBC, at the time, had a fondness for live outside broadcasts looking at a location over a day or weekend. For example, Badgerwatch involved a sett of badgers, with regular reports on the action therein. Ghostwatch purported to be that sort of thing, from a site of alleged poltergeist activity. Michael Parkinson was the studio host, with Mike Smith manning the phones, and studio “experts” to provide colour commentary. Out on location, Sarah Greene was inside the house with the residents (a mother and her two daughters), while Craig Charles loitered outside.

Eight years on and fully aware of its dramatic status, it’s still impressive and scary. Initially, all is calm – ­even dull – and when something finally does happen, it has perfectly mundane origins. But in the background is a bunch of unsettling stuff, slowly developing. The studio gets a load of phone calls about a cloaked figure seen lurking in the background of some video footage; residents tell of recent disturbing events, such as the ritualised killing of a black Labrador; and the history of the area is slowly revealed. In true Blair Witch style, it dates back generations, with the most recent incarnation of evil a serial child-killer. This sets the scene for the last thirty minutes, which escalate from noises off to…well, let’s just say if it goes over the top at the end, it has already landed the audience by then. En route are genuinely hair-raising moments, such as near-subliminal glimpses of figures lurking in shadows or behind doors – after all the phone-calls on exactly this topic, it’s amazingly effective. You can imagine BBC phones melting as thousands called in to say, “I saw it!”

Parkinson and Greene are excellent. They’re largely just playing themselves but, crucially, come over as wholly credible. Craig Charles – the presenter with most acting experience – is satisfactorily idiotic, while Mike Smith is weaker, especially when trying to show “concern” for real-life other half Greene. The genuine actors, however, seem stilted; obvious thespians rather than the real people they are portraying. Once things start to happen, all such problems evaporate, perhaps because “running around and screaming” are easier than pretending not to be acting. This is pretty basic material, the stuff of camp-fire tales, yet its primordial power is apparent in the quavering voice of a genuinely disturbed continuity announcer, after the play finishes with Parkinson all alone in a dark studio.

This was television drama at its finest and most disconcerting, and perhaps also the nearest Britain has come to a War of the Worlds style panic, surpassing even the conspiratorial SF of Alternative 3. It’s a stark reminder that, even in these supposedly sophisticated days, you can still fool a lot of the people, for ninety minutes of time. Indeed, it’s probably good to do things like this every once in a while, if only to remind the population that you really shouldn’t believe everything you see on TV…