"By Mozart and Friends" runs the composer credit for Der Stein der Weisen - The Philosophers' Stone - even though Mozart's name is on only three brief numbers. These credentials were established only around a decade ago, though, so Garsington's offering for Mozart year has novelty on its side.

First presented in 1790 by Emanuel Schikaneder, who would stage Mozart's The Magic Flute the following season, the work was a team effort by at least five different composers, including Schikaneder himself and the singers who would create the roles of Tamino and Sarastro. It shares with Flute not only the personnel but its mixture of speech and song, its fairytale flavour and, loosely, its roster of characters. On paper, it's fascinating.

On stage, it's not. It's entertaining enough, in John Cox's often inventive staging, and Peter Ruthven Hall's designs make good use of the old house walls around the semi-open stage. But it plays more like a clunkily paced panto than a prototype masterpiece. More laughs could have been had if the comic couple of Lubano and Lubanara - snappily played by Leigh Melrose and Teuta Koco - had been allowed to deliver their punchlines in English translation.

As for the music, you can't necessarily tell what is Mozart, but you can almost always tell what isn't. The most attractive arias turn out to be those the conductor Steuart Bedford has purloined from other Mozart works to fill in the gaps - and when Melrose, an ENO Papageno, huffs out a few bars of one of the birdcatcher's arias from The Magic Flute on his mouth organ, it reminds us what we're missing.

The cast is good, with Amy Freston an elegant heroine and Eutifronte, looking like a blue-painted ewok, sung with villainous bluster by Michael Druiett. As Nadir and Astromonte, tenors Ashley Catling and Iain Paton make good stabs at impossibly stratospheric arias. The orchestra sound decent if not always vivacious. But it would take alchemy indeed to make gold out of this.

· In rep until July 10. Box office: 01865 361636