With Exhibition Road turned into a fair - acrobats and jugglers, exotic foods and folk singers, and the charity-cycling Olympianist pounding out his music from the back of a lorry - the Proms must work to keep their audience.

No problem about filling the hall, however, when it’s Bach’s ‘Mass in B minor’. The original purpose of this vast work is a mystery, since it was far too long to fit the liturgy of any church, and it had to wait more than a century for its first complete performance.

Its first publisher described it as ‘the greatest musical work of all times and nations’. And - whether sung by one or fifty to a part - that is exact: it may consist of many smaller works recycled by Bach in his maturity, but it was designed by him as his crowning achievement.

Radio 3’s naff Olympic lighting seemed particularly out of place with the warm, golden sound which Harry Bicket’s period-instrument English Concert and its choir produced for this occasion.

They wisely went for the slow burn, letting the massive opening fugue of the Kyrie generate its own momentum. But not all the soloists seemed at ease: soprano Carolyn Sampson sang with flexible lightness but failed to project through the big space, while bass Matthew Rose was patently out of his depth.

Backed by three flutes, soprano Joelle Harvey and tenor Ed Lyon made an excellent pairing, however, while counter-tenor Iestyn Davies was his usual peerless self, sending his big sound up to the gods with effortless grace.

This work’s structure is based on symmetries, with the key one reflecting the Credo’s position as the corner-stone of the Christian faith, and in this section the chorus were magnificent. Powered by Bicket’s rock-steady tempo, the ‘et incarnatus est’ seemed to well up out of the earth, with the burial section going back down into it before the electrifying ‘et resurrexit’ doubled the pace; at the expectation of general resurrection, these fine choristers went out in a blaze of trumpet-fuelled glory, buoyed by the rolling waves of their polyphony.

Albert Schweitzer described this work as being ‘as enigmatic and unfathomable as the religious consciousness of its creator’, and that’s how it felt here.