When a musical superstar films a profile, the TV companies go all protective. The BBC did it with its Arena of Bob Dylan by Martin Scorsese. There were absolutely no preview DVDs, just a once-only screening at the NFT. It all helps to build the sense of an incredible event, even if the real concern is preventing pirate copies getting out.

Channel 4 has done something similar for I’m Going to Tell You a Secret (Channel 4, Thursday), the new two-hour “behind the scenes” film of Madonna’s 2004 Re-Invention tour, timed to promote her new album, Confessions on a Dance Floor. Hacks had to book private viewings at Channel 4 HQ, under the watchful eyes of staff. They didn’t actually frisk me when I left — just made a joke about it.

It certainly is “event” TV. For paid-up Madonnistas it should be pure gold. There are barnstorming numbers from the shows where she struts and gyrates like an acrobat. The sets are spectacular, the dancers beautiful, and the costumes exceed the dreams of the maddest fashion designers. Gullible members of the cult might even believe that the hours of “real” black-and-white footage give access to their idol in unguarded, private moments. For the rest of us, it’s fascinating for a different reason.

Twenty years ago, when the “Queen of Pop” was a rebel princess, pushing the boundaries of pop-video sexuality, thrusting an arm up the vestments of the Catholic Church and generally “reinventing” herself every five minutes, she became an icon of the feminist movement.

Earnest academic conference papers described her as an empowering role model for adolescent girls. Some of the wackier American universities offered degrees in Madonna Studies. Perhaps they still do. If so, they should definitely make use of this film. It is a masterclass in irony-free egotism: a lesson in the triumph of style over substance, a dire warning of the way unwary mega-stars can drown in their own hype.

Co-executive-produced by Madonna herself, the film has been cherry-picked from more than 300 hours of footage. Captions in Madonna’s own handwriting lend intimacy to her secret thoughts — such as: “There’s more to life than fame and fortune. Something deeper and more profound.” Or, more vaguely: “Obey the laws of the universe.”

Before each show the troupe hold hands in a circle with Madge as she gives a pep-talk. “Let us take the audience to a greater plane,” she says on the opening night, “and inspire the people to be better versions of what they are already.” By watching Madge prance around in camouflage trousers and a beret like Pattie Hearst or Che, presumably.

She sometimes treats her entourage to poems, which she readily admits are “witty”. One begins like this: “I have a cage. It’s called the stage. When I’m let out, I run about.” And it just gets better. When we see husband Guy Ritchie (credited among the “Talents” as “My Old Man”) giving her a foot-massage, she proves her candour by implying he’s only doing it for the camera. Yet when Ritchie protests he does it quite often, he’s the one sounding sincere.

At the end she tells the troupe tearfully that she regrets she did not have time to hang out with them more, because she does have another family. Yet she also regrets not hanging out with her children either, complaining that “the nanny gets to have all the fun”. The much-reported “revelation” about a row with Ritchie, by the way, sounds like a prepared statement.

All of which might be tolerable if the film weren’t steeped in pseudo-mystical kabbalah-inspired drivel. It ends with her pious reflections on controlling her own ego, played over a screen-filling image of her face overlaid with heavenly cloudscapes. And this is just a tiny sample of the film’s riches. It’s an historic film all right, but not quite in the way C4 (and, presumably, Madonna) thinks.

I’m Going to Tell You a Secret, Thur, Channel 4, 9pm

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