Arvo Pärt and John Tavener are obvious concert partners: both are best known for music that is characterised by a pure, simple sound, inspired by a deep search for pure religious expression, stripped clean of messy human emotions, a style known as ‘holy minimalism’. Their careers too have followed similar, and familiar trajectories, with daring, rebellious experiments gradually settling into a more accessible maturity, as the two composers became fixtures of the musical establishment, with Royal funerals, King’s College commissions, Grammy awards, best-seller CDs, a knighthood and honorary doctorates between them.

Although the two composers are so closely linked in the minds of the general listener, the two halves of Royal Northern Sinfonia’s Late Mix concert of instrumental works were surprisingly different. The three works by Pärt which occupied the first half were text-book examples of Pärt’s ‘tinntinabular’ style, in which the harmonies and textures are derived from the sounds of bells but the Tavener piece, Kaleidoscopes (A tribute to Mozart) was much more complex.

Even the staging for Kaleidoscopes  was unusual, and was reminiscent of the flamboyant Tavener of the sixties who hung out with rock stars and collected cars: four string quartets, arranged in the shape of a cross, with a solo oboist, dressed all in white directing proceedings from the centre. I suppose he was meant to be a priest or a Christ, but something about the theatricality of it made me think of him being a Pierrot figure.

The music itself scatters around distorted fragments of Mozart melodies, in various moods, sometimes serene, sometimes decidedly sinister with choppy repeated chords, or just cheerful, such as the passages of vibrant trills and pizzicatos towards the end, and the overall effect was often like hearing someone trying to hum a tune that they can’t quite remember. The strings of Royal Northern Sinfonia caught the anarchic spirit of the piece, especially at the moments when they were called on to break out into tiny bursts of absolute racket and at the end the low strings made the most of the brief moment when they were allowed to be loud and exciting.

The solo oboe holds it all together, and is a truly punishing part – thirty minutes of mostly very high, sustained playing that demanded awesome control and skill from Steven Hudson. In the opening passage that repeats through the music, the oboe was so high and clear that it seemed to blend in completely with the high violins, and yet throughout the piece Hudson played with a sweetness and musical sensitivity that transcended the fearsome technical difficulties.

I imagine that there were few technical difficulties in the three pieces by Arvo Pärt in the first half, but that doesn’t mean they’d be easy to play well. Fratres  glowed with the pleasure of simple, clean music as the chant-like melody ebbed and flowed; the nine violins seemed to breathe as one as the piece began and in all three Pärt pieces the orchestra communicated with each other with the intensity of a string quartet, without any obvious direction, The double-basses are the real heroes of this piece though; Pärt’s melody hangs off the single thread of their continuous pedal note, which must have been very boring for them to play, but they still had to drive the dynamic changes, and the piece would be nothing without them.

Summa, like Fratres, is another of Pärt’s pieces that exists in different formats, including vocal settings of text from the Creed. The Royal Northern Sinfonia strings gave it a calm confidence, creating music so sure of itself that it doesn’t need to be dressed up with complexity. The eternal argument with Pärt’s music is whether it’s just shallow easy-listening or whether there is spiritual depth in its purity but what I took away from tonight’s performance is that the listener is as important as the players; if Pärt’s music just comes on the radio when you’re doing something else, it can wash over you and sound facile, but it becomes something much more meaningful when you sit very still in a concert hall, and let yourself be absorbed into it.

Matching Tavener’s tribute to Mozart was Pärt’s Cantus in Memoriam Benjamin Britten. Pärt’s writing here reminds me of the final movement of Britten’s last string quartet, in which the bells of his beloved Venice toll against the gently lapping waves. Royal Northern Sinfonia played with sensitivity to the inarticulate grief that suffuses this piece and they reacted to each chime of the bells with the tiniest increase in the emotional pitch of the music, showing how Pärt’s music can be intensely beautiful, but never ‘easy’.