The idea of adding an extra movement to Holst's Planets ought to be shocking. Yet the lack of public interest generated by this mild piece of iconoclasm is rather sad. Perhaps the fact that Colin Matthews's extra movement, Pluto, has been so effortlessly accepted into the Hallé's repertoire since its premiere two years ago has something to do with the closed nature of concert performance. Or perhaps it's because The Planets doesn't strike us as an emotional work on the scale of, say, Elgar's Enigma Variations - imagine adding an extra movement to those - and so we don't feel protective about it.

In fact, the only aspect of Holst's original that is affected is Neptune's magical ending, and Matthews has taken immense care not to detract from that. That means beginning Pluto just before Neptune is quite finished, and then returning to Neptune's offstage sopranos right at the end. Matthews references the previous movements quite distinctly: the implacable tread of Mars is a near-constant presence under a surface texture dominated by the flitting celeste and harp textures of Mercury. It was all beautifully shaded and controlled, with Mark Elder's sensitivity to orchestral colour informing the whole performance.

It may be that not all music responds equally well to such sensitivity. In a strong performance, Walton's epic choral work Belshazzar's Feast can pack a punch. Treated too gently, it can sound insecure. Here, neither the Hallé choir nor the orchestra seemed to be enjoying themselves much. The choir sounded thin and strained, even lost at times. Elder captured some aspects of the work's inner drama well: the chorus acclaiming Belshazzar shortly before his death had a striking hysterical edge. But despite such rare subtleties, and a fine performance from baritone Peter Coleman-Wright, the Hallé's Belshazzar was on the limp side.