Themes of spirituality and religion pervaded the fourth and final chamber music prom of this BBC Proms season. Cellist Nathalie Clein joined the BBC Singers and the Britten Ensemble under conductor David Hill to perform works by modern composers with an interest in the esoteric; Micheal Tippett, Sofia Gubaidulina, and – seated in the audience for the UK premiere of his Popule Meus – Sir John Tavener.

Although a professed agnostic himself, Tippett's compositions occasionally engage with religious themes and take religious texts as their inspiration. The Windhover takes a poem by Gerard Manley Hopkins, which uses the image of a vividly observed kestrel on a bright morning to proclaim Christ's piety. The poem's architecture is exaggerated by Tippett's musical pen, which treats the text to his typical skipping, hopping rhythmic style and extended melody lines. Within Tippett's text setting, the music can be seen to constantly 'act' upon the words, rather than carrying them, adding a greater sense of drama. Harmonically, the composition consistently throws its text into new relief by evocative tonal shifts at moments where the text pays reverence to religious symbols or persona with the effect of 'layering' the work's profundity. By combining a powerful religious image with emotionally resonant musical phrase, Tippett forges a satisfying and emotive articulation religious concepts which are otherwise vague. Hill's conducting was true to the work; always fresh and crisp, crystallizing the lucidity of the textual image. Likewise, in Plebs Angelica – whose text plays homage to the virtue's of heaven's angelic host – Hill was highly articulate, the interpretation not rhythmically weakened by an attempt at portraying the nebulous subject matter.

John Tavener's new composition Popule Meus concerns the flight from the modern, materialistic world towards a deeper sense of truth. Through a musical conversation between the timpani – which represents man turned from God – and the Cello – which represents the all-compassionate profession of faith, Tavener argues that the rejection of god is in vain, that we live in a world of illusions, and only The Absolute is real.

The composition gave full dramatic weight to the oft-ignored consequences of this philosophic debate, and Clein's facial and figurative expressions conveyed the full burden of a true religious protagonist; she appeared to have 'lost herself' whilst obviously maintaining masterful control. Although, aesthetically, she looked fitting, her notes transcended her image to a point where the musical effect produced was so intense as to almost appear unrelated.
Musically, the argument that Tavener proposed was quite straightforward. The cello's compassionate avowal of God's existence was executed by its relationship with the ensemble, with which it was dominant over, yet united with; always harmonically supported and complemented, blending in and out of the weaker string textures.

In contrast, the Timpani's individualistic approach to the ensemble – which was obviously a metaphor for a monist universe – surfaced in disjunct sections which rebutted, crudely interjected and fragmented the otherwise smooth and melodious writing. Both as a composition, and as an analogy, Tavener could have made his work more interesting by lending credence to the opposing side of his argument; the timpani part. Although undoubtedly the bias was for a specific purpose, the timpani rhythms didn't evolve throughout the composition, and became slightly dormant.

Tippett's Little Music for string orchestra made a light interlude between the conceptually heavier items on the programme. Influenced by the baroque style, particularly Purcell, Tippett takes light, baroque-like idioms and treats them to a dose of modern tonality and counterpoint, using a ground bass (repeated bass line) as a structural centre. The Britten Sinfonia proved a wonderfully sensitive vehicle to Hill's precise baton, with the ability to squeeze from themselves a tremendous dynamic range and to form indistinct and subtle sonorities, effortlessly; particularly exhibited in the composition which utilizes the full power and grain of texture of a string ensemble. Repeated rhythms were sustained with brilliant energy, the work never dragged or became heavy. Each phrase in the patchwork counterpoint was neat and defined, making the tutti sections even more momentous.

'Continue down your mistaken path' was Dimitri Schostokovitch's advice to Sofia Gubaidulina, when he recognised her distinctive persona and maverick tendencies as her tutor at the Moscow Conservatoire. Like Sir John Tavener, the source of Gubaidulina's work pours from a highly personalised set of religious beliefs, leading her towards an idiosyncratic musical language, often featuring unusual combinations of instruments. The last and most onerous item of the programme, The Canticle of the Sun, uses an Italian text by St. Francis of Assisi which praises God and his creations for their magnificence. The setting of the text varies in its degree of freedom and repetition, sometimes emulating a congregational chant, sometimes breaking through the tight form of the text into freer textures. Although it is the cello which has the main role within the work – it is, effectively, a cello concerto – the vocal passages are, in places, extremely diverse; the BBC singers utilized an interesting range of vocal textures, some singers permeating the musical surface to make individualised contributions, appearing as plaintive outcries of devotion.

During the performance, the cellist's role is extended to play the gong and the tam tam in the manner that would occur in a ritual or ceremony; Clein did so with a convincing air of spiritual authority and slow, deft movements. Gubaidulina's composition gives silence the same value as sonority, alluding to spiritual states of reflective contemplation. Clein's acute level of rhythmic articulation and succinct mannerisms gave the ensemble an energy that loaded any music pauses into intense moments of tense anticipation; the effect of any subsequent bow slap or motif was amplified to cut maximum impact. Ultimately, the cause of the performance to transcend itself, and the main strength of Clein and Hill's interpretation, was to push the energy and tension brought about by tight rhythmic articulation rather than veering towards a looser, more expressive interpretation which would have matched the nebulous subject matter, but not revealed the work's true potency.