Prom 40: BBC SO & Chorus / Boulez, Royal Albert Hall, London

There was some surprise when it was learnt that Pierre Boulez, a conductor of immaculate precision, had taken to performing that sometimes rough diamond Leos Janacek. But with his recent readings of Janacek's last opera, From the House of the Dead, having drawn rave reviews, one approached this Prom of his music from 1926 (well into the Czech composer's prodigious old age) with real anticipation.

Janacek's Sinfonietta, with its virile opening and closing fanfares for massed trumpets and its often quirky and pungent movements, one would have thought unsinkable. Yet Boulez seemed scarcely engaged beyond calmly beating time and giving cues. Where was character and thrust? Nor was the capriccio Defiance entirely happy. Admittedly, it is an eccentric piece even for Janacek. Composed for the Czech pianist Otakar Hollman, who had lost his right arm in the First World War, this four-movement concertino is backed solely by seven brass instruments, plus flautist. One had hoped that that most sensitive French pianist Jean-Efflam Bavouzet might make something of its whirling scraps of material. But, for no obvious musical reason, the piano was set facing diagonally upstage, seriously diffusing its sound.

The second half was on a different level. Janacek's Glagolitic Mass alternates choral writing of numinous strangeness and wild fervour – especially as heard here in its original version, before Janacek modified some of its boldnesses. The second of its two orchestral introductions already superimposes three tempi; the penultimate movement comprises a crazily jubilant organ fantasia.

Something in Janacek's atavistic gawkiness evidently got to Boulez, for he proceeded to direct the combined BBC Symphony Chorus, London Symphony Orchestra and BBC Symphony Orchestra in a performance of real focus and drive. A pity the solo line-up was marred by the wobbly soprano of Jeanne-Michèle Charbonnet, though the New Zealander Simon O'Neill produced an authentically Slavonic-sounding high tenor, and Simon Preston revelled in the organ movement.