The Excursions of Mr Broucek is the odd man out among Janacek's operas. Its vagaries, in many respects, are intensely bound up with the history of its genesis. Janacek worked on the score for nearly 10 years, and no less than eight writers had a hand in the libretto. Its discursiveness is compounded by Janacek's choice of a subject that some have considered unsuitable for operatic treatment.

Broucek, an alcoholic Prague landlord with a vivid imagination, first saw the light of day in a series of tales by the writer Svatopluk Cech, who ruthlessly satirised the Czech bourgeoisie for its cultural philistinism and its failure to maintain a sense of national identity under Austro-Hungarian rule. Janacek effectively makes Broucek the protagonist of a pair of contrasting one-acters: first by letting him loose among an effete colony of aesthetes who live on the moon, then by transporting him back to the time of the Hussite rebellion, where his obsequious attitude to the Austrian invaders exposes his fundamental cowardice.

The lunar episode, despite some passages of great lyrical abandon, has considerable longueurs, which even a performance as good as this can't quite disguise. Jiri Belohlavek conducted the BBC Symphony Orchestra with formidable passion throughout, but the opera only really takes wing in its second half, when stirring choruses and ricocheting brass figurations finally mark the emergence of Janacek's mature compositional voice and usher in music as daring as anything he wrote. Jan Vacik was the fine, dithering Broucek, Maria Haan and the great Peter Straka played the feuding lovers Malinka and Mazal and their incarnations in each of Broucek's visions. It was all thrillingly done, though the work itself is ultimately no masterpiece.

· Broadcast on Radio 3 on Thursday.