Collegium Vocale Gent/Herreweghe, St John’s Smith Square

Under the imaginative direction of Lindsay Kemp, the annual Lufthansa Festival of Baroque Music has always punched above its weight, and this year’s programme is no exception.

Kemp has created a musical journey through the heart of eighteenth-century Europe, starting in the Hanseatic Baltic ports and ending in the Venetian lagoon: his purpose is to remind us of the forgotten but remarkable composers who toiled alongside the ones we know. Besides Bach and his musical father-figure Buxtehude – to meet whom, the young Bach humbly made a 250-mile pilgrimage on foot – we will also get a posse of Polish and Bohemian composers whose music is almost never heard in London.

The festival opened with the work which Albert Schweitzer found ‘as enigmatic and unfathomable as the religious consciousness of its creator’: Bach’s B minor Mass. This was Bach final masterpiece, and he didn’t so much write it, as compile it from his own elaborations of earlier works, and its original purpose remains a mystery. It’s in the normal liturgical form, but at over two hours it was too big to fit into any church service. The accepted view now is that he wrote it as a summation of everything he had written for voices and instruments, as his musical message to posterity.

Performed as it often is by a chorus of hundreds, its effect is massive from the first thunderous phrase; delivered as it was here, with 18 singers plus an instrumental ensemble of similar size, it took a while to catch fire, but when it did the effect was no less overwhelming.

As one of the oldest hands in the early-music renaissance, the Flemish conductor Philippe Herreweghe knows that if you let this work start at a gentle, regular pace with no forcing of effects, it will flower of its own accord, and here the choral sound was beautifully focused, the instrumental playing exceptionally clean.

The acoustic of St John’s can be hard for soloists to negotiate. But while soprano Hana Blazikova underestimated the projection needed, her co-soprano Dorothee Mields gleamingly found the spot, as did tenor Thomas Hobbs; the voice of the evening was the clarion-toned counter-tenor Damien Guillon. The choral fugues gloriously took wing, with the three central choruses – ‘Incarnatus est – Crucifixus – Et Resurrexit’ – being as breathtaking as one could wish.