Mozart always knew how to give his audiences what they wanted, while also providing more than they bargained for.

The Archbishop of Salzburg commissioned him to write the first part (the other two are lost) of an oratorio on the theme of The First Commandment when he was just 11. Mozart responded with a mature and thoughtful drama, pious but with glints of humour, and sung to music that is effervescent, graceful and occasionally profound.

The Classical Opera Company makes a speciality of early Mozart and was bound to get round to it eventually. The crumbling Victoriana of Wilton's Music Hall is nothing like the Archbishop's palace, and Bill Bankes-Jones's production has its tongue further in its cheek than Mozart did, but only a curmudgeon would complain.

Nigel Lewis's English translation adds its own mischief: I suspect the Archbishop would not have been amused by lines such as: "Get up you lazy sod, it's time to meet your God."

The three Christian spirits of Mozart's original become thoroughly modern border guards, intent on policing the boundary between this life and the next, while the wavering Christian becomes a booze-soaked scruff, asleep in the transit lounge. There he is tempted by the Worldly Spirit, a good-time girl for whom every day is Christmas.

The jokes are fresh and witty, and the five young singers know how to communicate musically, verbally and physically; Madeleine Pierard (Justice) and Allan Clayton (Christian) are first among equals, finding the right, Italianate balance between sensuality and high spirits.

If the orchestra, directed from the harpsichord by Ian Page, is more rustic than refined, that suits the mood, and in Abigail Newman's alto trombone it has an instrument of rare poignancy. The First Commandment is no masterpiece, but it is much more than mere juvenilia.