The fervour of fans on the terraces

Robert King and his eponymous Consort won their spurs as stylish Handelians, tireless Purcellians and dashing Vivaldians, early music specialists united by a desire to entertain and divert their audiences. Entertainment and diversion featured strongly in the King's Consort account of Bach's B minor Mass at St John's Smith Square on Wednesday, thanks, in large part, to the contributions of the Tolzer Knabenchor, appearing in London for the first time in a decade and refreshing memories of the robust boys' choir sound favoured in Germany.

For all the verve and virtuosity reserved here for Bach's celebratory dance movements, deeper expressions of faith and its mystery were unhappily absent. Despite using only the finest performing ingredients, including a first-rate team of instrumentalists, an expert line-up of adult choristers, and soloists Anthony Rolfe-Johnson (tenor) and Michael George (bass), King's interpretation had the feel of work-in-progress, high spirited but not yet mature in vision, a convenient public rehearsal for forthcoming recording sessions.

The opening "Kyrie" suffered from an overall want of shape, its architecture supported on a bedrock of mannered phrasing and undermined by premature climax. Later, the more introvert, confessional sections of the Nicene Creed passed quietly by, presented almost as convenient moments for a breather between admittedly impressive deliveries of the monumental choruses with trumpets and drums. For example, traces of an emotionally charged "Crucifixus" were bound firmly to the earth by King's inflexible response to the text; likewise, the "Et incarnatus" was short on expressive subtlety. In the "Benedictus", Anthony Rolfe-Johnson, in partnership with Rachel Brown's mesmeric flute-playing, offered an exquisite masterclass in refined verbal inflection and nuance, qualities all too often absent elsewhere in this performance.

Gerhard Schmidt-Gaden's meticulously prepared "Knaben" gave good value, as both choristers and soloists, projecting a bold, full-blooded and often hard-edged sound, uncannily rich from the mighty-atom altos. The two treble soloists in the "Christe", uncredited in the programme book, were the coolest of customers, brimming with confidence and a sense of fun. The Tolzer boys are encouraged to sing with a more open sound than the average English cathedral or collegiate chorister, a technique requiring frequent intakes of breath and often creating fragmented phrasing, highlighted here by King's puppet-on-a-string conducting style. Prolonged exposure to such full-throated tone triggered an alarming number of sympathetic coughers in the packed St John's audience, no doubt reflecting subconscious desires that the Tolzer boys might present more light and shade in their singing.

What the Tolzer Knaben lacked in tonal variety was more than offset by their refreshing blend of enjoyment and professionalism, qualities not always connected. There were consistently valiant efforts from each of the pre-pubescent soloists, small-lunged chaps faced with the superhuman demands of Bach at his unrelenting best. The boys were at their finest in Bach's most flamboyant choral writing, announcing the "Gloria" with the fervour of fans on the terraces at Bayern Munich: their second statement of the words "Et in terra pax" ensured that peace was delivered with a mailed fist. The "Cum sancto" and "Et resurrexit" fugues, launched imperiously by the faultless Crispian Steele-Perkins and his trumpeting partners, danced along without a hint of Lutheran austerity, preparing the way for an explosive "Sanctus" and triumphant "Osanna".