By definition, there aren’t many occasions on which anyone can remember where they were ten years ago, to the day – but Sunday, September 11, 2011 was inevitably such a day. For those of us who adore the USA and New York in particular, it was somehow essential to be somewhere special, where our personal moments of reflection and shared pain would be apposite.

Taken at face value, Cheltenham was perhaps an odd choice, but surely it must be an unspoken aspiration of every seasoned concertgoer to be present – by accident or design – at the premiere of a genuinely great work. In October 1997 I happened to be attending the Conservative party conference in Blackpool and I confess it crossed my mind beforehand that it would be interesting to hop onto a cross-country train mid-week in order to attend the first public performance, in Manchester, of the original version of Gustav Mahler’s first big concert piece, Das Klagende Lied. Fate intervened, however, because I was staying in the same guest house as senior Conservative politician Ken Clarke, whose unsuccessful leadership campaign I had helped to run during the summer – and I ended up as his de facto right-hand man once more, when the media judged him to be a bigger story than the man who beat him, William Hague, and he needed a minder. To my shame, I forgot about Mahler for the entire week.

Now perhaps that immature work by the Bohemian master would not qualify as a great work, but I suspect that noble mantle may ultimately fall upon Richard Blackford’s oratorio, Not in Our Time, which has just been premiered in Cheltenham Town Hall. Having recently signed off a book that deals with the dangerous interactions that can exist between religious fundamentalism and democratic politics, perhaps this work speaks to me with particular acuteness and power, but the stunned audience in Cheltenham seemed to be similarly affected. They had already been softened up with a perfectly judged first half programme, featuring both the Bournemouth Symphony Orchestra and Simon Callow in superb form – special mention to the trumpets – in Copland and Barber. How fortunate we are to live in the era of Callow – a reader not a singer here, yet so musical and also utterly moving as he stopped time and prompted tears with his potent declamations of democracy and freedom. It was a perfectly judged decision to give us not only the generous, liberal sentiments of George Washington and Thomas Jefferson, but also a full version of Tom Junod’s extraordinarily elegant, heart-breakingly poetic description of one of the “jumpers” from the World Trade Center on 9/11, part of which has been set in Blackford’s oratorio. That must have been so much easier to set than the clunking, lumpish rhetoric of George “Dubya” Bush, with his talk of crusades, or the hate-filled outbursts of his fundamentalist Islamist opponents.

Not in Our Time stands in a powerful tradition of English oratorios that are highly political and overtly pacifist, drawing upon texts old and new to make the link – at once inspiring and depressing – between the contemporary and specific on the one hand, and the timeless and absolute on the other. As an unashamedly liberal Tory, I believe what the world needs now is a message of healing, of moderation and shared humanity – and that is precisely what Blackford provides in this new work. It may take a while for his natural optimism to break through, but when it does, it is glorious. Drawing alarming parallels between the Christian-Muslim conflicts of 900 years ago and the comparable miseries of today, he forces his audience to look in the eye a profound, hideous truth: century after century, men (and, yes, it is invariably men) abandon their shared humanity all too readily, using religious rhetoric to inspire nauseating atrocities. The texts used are alternately shaming and moving – and both the lyrical inspiration and the orchestration are of this highest level. String configurations hypnotise and the cor anglais enchants, then the band breaks in with its martial anger. At the premiere, no praise could be high enough for the Bournemouth Symphony Chorus, whose centenary the work was courageously commissioned to celebrate. Soloists Paul Nilon and Stephen Gadd projected superbly, alternating symbolically and then combining with authority and style, and conductor Gavin Carr marshalled his forces with compelling authority.

Yet this concert was ultimately about the new piece itself. Having studied only the vocal score, I had already presumed to compare this piece with two previous works – Michael Tippett’s A Child of Our Time and Benjamin Britten’s War Requiem. In concert and fully orchestrated, Not in Our Time is perhaps closer to Tippett than to Britten – rooted in tonality whilst pushing at its boundaries when anger strikes – but both influences are palpably there, without the slightest hint of it being derivative. Invention is all – and there is invention aplenty. A more surprising parallel is with Leonard Bernstein – the Lenny of the Chichester Psalms and the Kaddish symphony, full of simple yet infinitely complicated love and a desperate aspiration towards shared humanity; Abrahamic ecumenism as art. At one point the first trumpet is a touching shofar in all but name. This is a paean of and to hope, a proclamation of shared humanity and, above all, a great oratorio for the peacemakers. Those who missed the inaugural performances in Cheltenham and Poole may wish to explore the recording that Nimbus Records will be issuing in November. This is a serious piece, but infinitely rewarding. Frankly, the more people who listen to it, the better, happier and more at peace with itself the world will be.