The trouble with music that’s couched in the rhetoric of transcendence is that the interpreter has to try to live up to those terms in performance. In the case of John Tavener’s The Protecting Veil the bar is set high from the first page of the score with the composer’s direction: “Transcendent, with awesome majesty”. Luckily, Matthew Barley’s performance of the work with the City of London Sinfonia – part of its Modern Mystics trilogy – for the most part delivered on Tavener’s direction by bringing to life the depths and contrasts of this deceptively simple piece, making for an absorbing presentation of Tavener's musical ecumenicism.

Starting a performance of a work of such overt mysticism as Tavener’s with a lecture-like explanation of its theological underpinning and musical devices seems, on paper, like a sure-fire way to sap the concert of its emotive power. But with his “living programme notes” Barley did a good job of elucidating, without giving too much away, how Tavener uses simple compositional techniques to create intensely moving music. Barley moved sections of the string orchestra around the space, playing them off each other in antiphonal responses and applying techniques like augmentation and canon to well-known Christmas carols to demonstrate how they work in Tavener’s piece. Serious fans might scoff, but I’d argue it’s a great way to help more casual listeners appreciate the hidden depths of the music.

It wasn’t until after the interval that the orchestra actually launched into the piece itself. At the outset, the anchoring drones set up by the double basses could have been more prominent, and it felt as if it took a few moments for the orchestra to warm up and mesh with Barley’s solo playing. This slight feeling of reticence quickly melted away, however, and we were left to enjoy how the shimmering textures of the orchestra complemented the continual song of the cello. Constantly in the foreground of the sonic picture, cellists who front this piece run the risk of sounding cloyingly sentimental if they overdo it on the vibrato. Barley, however, stayed on just the right side of sounding weepy. He has a longstanding relationship with the piece and this showed in the way he was able to imbue the more free-flowing passages of the cello writing with an almost improvisatory feeling. In the opening talk he had demonstrated, with the help of an electronic tambura, how Tavener’s stated use of glissandi and quartertones in these sections related directly to the meend technique used by instrumentalists in Indian classical music, and in practice he was able to execute this with aplomb, bending notes and furrowing forward in passages of ecstatic virtuosity. In the Lament section, the broken-sounding centre of the piece where the soloist is at its most vulnerable, Barley created a suitably smoky atmosphere, teasing strange textures from his muted instrument.

Credit should go to the orchestra for the sensitive ways in which they complemented the solo instrument. The stacked chords of the Nativity sections shimmered with reverent light, blurring the line between string instruments and the peal of church bells. In the aforementioned Lament, shrieking string clusters vividly reflected the pain of the Crucifixion, and in the depth-charge glissandi moments that punctuate the sections of the work the feeling of fathomless depth was well-rendered. At the close of the work, the disorienting glissandi that form the backdrop to the cello’s dying statements were unsettling and absorbing – a disturbing postscript to a work that is for the most part dominated by meditative calm.

In the 1990s, the Japanese psychedelic group Ghost sang about a “Guru in the echo”. For Tavener, writing The Protecting Veil a decade earlier, it seems that God was actually in the glissandi, and throughout most of the performance the City of London Sinfonia seemed alive to the composer’s sense of the spiritual significance of each of the work’s sections.