THE Passiontide Festival at Merton College, Oxford, remains one of the treasures among musical events heralding Easter. Its choir is now rightly famed as one of the best in Oxford and Cambridge.

The choir’s reflective main contribution under its director, Benjamin Nicholas, was a performance of Bach’s St John Passion, notable for its period instruments — the 17-strong Instruments of Time and Truth, founded by Edward Higginbottom — and its expressive tenor Evangelist, Ruairi Bowen, son of the organist of Hereford Cathedral.

Within a packed three days, the festival drew in a clutch of visiting soloists, including violin (for the complete, extraordinary Mystery Sonatas of Heinrich Biber, 1644-1704) and organ: Matthew Owens, acclaimed former organist of Wells and Belfast Cathedrals, introduced Howard Skempton’s second set of 50 Preludes and Fugues.

Skempton (b. 1947) is invariably an interesting, fresh, and intriguing composer, who over several decades has forged his own path, constantly innovative, indeed brave, engaging fascinating simple formulae, often reducing his vocal or instrumental lines to the barest minimum.

One arresting, original aspect of this extended organ series is the variety of duration (some last only 15 seconds, others are a couple of minutes) and the way in which he makes varied, often subtle, manipulations (it seemed) of a falling three- or four-note motif, conversely sometimes rising, to generate a myriad different effects.

Thanks to Owens’s unsurprisingly masterly manipulation of registrations on the Merton organ, installed ten years ago by Dobson of Iowa, simple use of diapasons (no. 1, forte), or indeed one diapason alone; an expressive pedal under an oboe-like solo (no. 2); soft starts in the pedal alone (no. 4); rocking gentle reed over a woody pedal ostinato (no. 7); or intricate flutes (no. 5) wallowing and ebbing as beguilingly as Smetana’s Vltava) proved, each in its way, mesmerising.

A number of movements, even when brief, were enchantingly joyous: lower-pitched flutes, piquant as a Daquin noël (no. 9); folk-like patterning in hands and feet, riveting as a Slavonic dance; or rapturous bell-chimes (no. 30); dancy diapasons (no. 36). Chromaticism is occasional (e.g. no. 27). Some movements sounded somewhat French (nos. 2, 34, 38). Where shyness or arcane confidentiality prevails (no. 41, furtive low reed, pppp) a sense of transcendent beauty reigns profound. Conversely comes the proclamatory: nos. 26, 44, or the ten-second no. 6; and the final, almost Lisztian no. 50. (I’ve tried to get these numbers approximately right.)

One absorbing detail is that Skempton eschews final resolutions: strikingly, he cuts off midway. This feels not jarring, but inspired. If there had to be criticisms, they might be that an identical key pervades several sequenced Preludes; or that where he embarks on counterpoint, one sometimes yearns for him to explore and develop his material further.