The Barbican is currently celebrating Shostakovich's achievement as a film composer, and I never expected to be moved by a Soviet propaganda film as I was last week by Podrugi (1936), in which the fortunes of three schoolgirls are followed through civil war. Shostakovich's soundtrack had a lot to do with its effect. But when New Babylon is screened on Wednesday, it will be with a score that was never intended as a soundtrack: Vladimir Jurowski will conduct a live performance by the London Philharmonic Orchestra.

This was Shostakovich's first shot at film music, at a time when films were routinely accompanied either by a pianist or a hack orchestra playing "quotes" from great composers. So, when this work with Shostakovich's experimental score came along, it was greeted with horror, both by conductors who said the music was unconductible, and by censors who insisted on cuts in its treatment of the Paris Commune.

The film was duly castrated, and castrated further when sold to Germany. While the full score lay hidden for decades, no complete print of the film survives. "I'm convinced that had this film not been banned, it could have ushered in a new era in Soviet cinema," says Jurowski. "It's now rightly bracketed in importance with the films of Sergei Eisenstein."

As a piece of vintage Shostakovich, the score contains the seeds of many great works yet to be composed: Jurowski loves its complex satirical games, one of which conflates the cancan with "La Marseillaise". And though he's daunted by the fact that the score is now, perforce, longer than the film, he reckons he can deliver the goods. "I'm trying to use my experience of Shostakovich as a composer, having performed his other concert works. I think I can guess with reasonable precision which music fits which sequence, and this helps me to find the right speed - crucial with Shostakovich. You have to know the film by heart - and I do."

8 November, 6.30 & 9pm (020-7638 8891; www.barbican.org.uk)