I was delighted when Martin Baker asked me if I would like to write a Mass for Westminster Cathedral because I had had one in mind for a while, and this commission encouraged me to get down to work. As I wrote it, and after hearing the first performance, I knew I wanted eventually to reshape it into a work for a large chorus and a large orchestra. A commission from the Indianapolis Symphony Orchestra was the catalyst for this second incarnation.

The central idea, and the central movement, is the Credo—in some ways the most problematic text to set because of its length and the non-poetic nature of the words. But instead of setting the words simply in a descriptive way, I wanted to explore aspects of the psychology which underlies the whole nature of belief and doubt. The Creed contains line after line of densely packed, carefully articulated theology—as watertight and restrictive as Nicea could make it. But I, like most Catholics, have said these words quickly, without thinking fully of the depth (or daring) of what is being expressed. And what does ‘believing’ in these pregnant clauses actually mean? When I stand and affirm that the Holy Spirit ‘proceeds from the Father and the Son’ what am I saying? And what about those who have ceased to believe and yet still rattle off blithely the bold print in the Missal after the sermon and before the offertory?

In my setting of the Credo I divide the upper from the lower voices as if innocence from experience. Only the sopranos and altos sing the word ‘Credo’, constantly interrupting the fast-paced mutterings of the tenors and basses. What at first is an encouragement to believe becomes a despairing cry as the men’s pattered rote turns into defiant unbelief. Only the clause about baptism is sung with any sense of faith—a last hope dashed as the final clauses about resurrection and eternal life fizzle out. A final ‘Credo’ is sung an octave lower by the upper voices—quietly, as if tired and shattered from their earlier, futile exertion.

The whole work opens with a brief, muted, unsettled chorale in the four horns (which we will later hear as the blazing series of chords punctuating the statements of the Credo). This moment of doubt lasts only for seconds and melts into the Kyrie proper, sung to music of sweet, simple consolation. The Gloria is joyful in its outer sections, based on an organ rising scale and a choral falling zigzag motif. In the central ‘Qui tollis’ section the zigzag motif pipes away in the piccolos’ repeated high chords, and the chorus now sings the rising scales. There are a few prophetic hints of the Credo here and there, in the ‘miserere nobis’ for example.

The Sanctus and Benedictus aim to contrast the divine and the human. The angels’ ‘Holy, holy, holy’ is something beyond the universe itself in grandeur and scope, and the music here is huge, broad, immense. In the Benedictus, Divinity has become Humanity in the Messianic incarnation, and the music is deliberately and sentimentally intimate—as if two people are sharing a drink in a Parisian café, with a whiff of Poulenc perhaps in the harmonies, or maybe even the sound of a distant 1950s pop tune coming from a neighbouring café’s jukebox.

The Agnus Dei takes the ‘Credo’ motif, sung by the upper voices, and develops it in a plaintive sequence. All is restrained and quietly expressive until the third, louder statement of the text, where the response should be ‘Grant us peace’. Instead of ‘peace’ the orchestra plays an interlude of mounting agitation and desperation based on chromatically altered fragments of the opening vocal chords. As this passage reaches its highpoint, with still no sign of ‘Dona nobis pacem’, the chorus sings a fortissimo ‘Agnus Dei’ to the music which had accompanied the baptism clause in the Credo. Finally, as a climax to the whole work, the ‘Dona nobis pacem’ is sung at highest volume and highest pitch—a variation of the descending scale first heard in the ‘Christe eleison’. The spell has been broken, all gradually becomes calm, and the piece ends musically as it began with the ‘Dona nobis’ sharing the same melody of consolation as the Kyrie, despite a fleeting fragment of the unsettled horn chorale from the work’s opening bars.

And why ‘Mirabilis’? Purely personal: I gathered my year’s-worth of sketches for this Mass together in September 2006 and wrote three of the movements in three days; the following day I had a serious car crash, overturning on the motorway at 80 mph; I stepped out of the one untouched door in my completely mangled car with my Mass manuscript and my body intact; I wrote part of the Agnus Dei in St Mary’s Hospital, waiting for four hours for a brain scan. I was conscious, as I was somersaulting with screeching metallic acrobatics on the M1, of feeling regret that I would never get to hear this piece. Someone had other ideas.

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