There was talk of protests outside the first screening of This Is It, as fans objected to a film they imagined would gloss over Michael Jackson’s ill health and the enormous pressure of practising for a 50-date run at the O2 arena. They needn’t have been so concerned. Jackson is alarmingly thin throughout and is, as befits a film composed entirely of rehearsals, mostly going through the motions.

Though This Is It reels through the smashes — and the set list shows it really would have been a greatest-hits affair, including some Jackson Five numbers — it’s always painfully obvious that this is a case of simply trying the choreography, working his way around the half-finished stage, resting his voice and saving the real oomph for the ticket-holders in London.

Of course, those concerts never happened, which makes this a bizarre and opportunist piece of film-making. At the beginning it’s made clear that most of the footage was shot for Jackson’s personal archive,and the rest, the expensive CGI, for use in the shows. It’s hard to know what the point is. If the film is supposed to stand as a memorial, it’s a poor decision — Jackson is shown as a perfectionist, so it’s unlikely he would have been happy with these sketches of performances being transformed into the main event. Nor does the film work as a substitute for fans who never got to see the show as it was intended, since it’s only the bare bones of what it could have been. This is a morbid curiosity, and doubtless it will be a profitable one, but shouldn't stand as the “final curtain call” that Jackson promised his fans back in March.

PG, 111 mins

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