There have been some great made-for-TV documentaries down the years, but that status as “TV programmes” means it’s kind potluck if they’re still readily available to us years later. Mark Cousins’s The Story of Film: An Odyssey? So acclaimed it got a DVD release and, recently, a Blu-ray upgrade. Mark Gatiss’s horror series? Too full of clips to be licensable. The Complete Citizen Kane? I don’t think this was available anywhere besides bootlegs, but will soon be included on Criterion’s 4K release of the film.

I could go on, but let’s stick to the one at hand. This feature-length Mark Kermode-fronted doc was screened at festivals in 1998 before being shown on the BBC in an edited form. Down the years it’s been available on some of the film’s DVD and Blu-ray releases, but only in that shortened version. Finally, 20 years after its first release, the unedited original cut popped onto the BBC iPlayer for Halloween 2019, and tonight it will be broadcast for the first time ever, on BBC Four at 11:55pm.

For those unfamiliar with him, Kermode is sort of the UK’s answer to Roger Ebert: a long-standing, widely-respected film critic across print, TV, and radio. The Exorcist is his favourite film, and (as he explains in a recently-shot introduction to this documentary) he’d written a book on it that its makers had liked, which led to him making The Fear of God.

As with almost any documentary about a specific film, your interest in it is likely to depend on your interest in the original film. So, assuming you care to know the behind-the-scenes story of The Exorcist, this is definitely a good film. I get the impression it’s the original source for a lot of interviews and stories that have been repeated around the place; ones that I’ve personally picked up through osmosis down the years. Despite that, I still learnt new stuff, and there are some nice moments to witness, like when novelist and screenwriter William Peter Blatty suddenly realises, on camera, how he should’ve written a scene all along.

If you’ve seen The Fear of God before (say, on one of The Exorcist’s physical media releases), how much this so-called “festival cut” is worth your time is a matter for your personal level of interest. Some DVD releases cut as much as 25 minutes out of the documentary, so if you’ve only seen that version then obviously there’s a lot of new material here. If you’re watching this version, you can be assured you’re seeing everything Kermode wanted to include as well as everything producer Nick Freand Jones wanted in. For example, there’s an interview with the woman who voiced the demon, who insisted her contribution was only in the BBC broadcast. Well, I guess this still conforms to that wish.

The Fear of God: 25 Years of “The Exorcist” is on BBC Four tonight at 11:55pm, or on iPlayer now.