John Adams’s most recent opera , A Flowering Tree, reached London this month in a reduced staging, ten months after its premiere: pretty good for time-lag Britain. With the previous opera, the bigger and bolder Doctor Atomic, concerning J. Robert Oppenheimer and the creation of the first atom bomb, London will have to wait until the 2008-09 season when English National Opera presents the British premiere, three years after its San Francisco debut.

Still, we’ve heard some of the music now: 45 minutes of it, stripped of sets, voices and Peter Sellars’s text collage, recomposed into a Doctor Atomic Symphony, unveiled to the world during Tuesday’s Prom. What a curious creature this was: not opera, not really symphony. When Hindemith distilled Mathis der Maler into symphonic form he did so with concentrated force and a structure of iron. Adams generated something wandering between a free-flowing fantasy and a film soundtrack CD.

As a guide to the opera’s stage activities, the symphony leaves the uninitiated flailing. The first movement, The Laboratory, was clear enough, maybe, with massive crunching dissonances, thumping timpani, lurching toward obsessive staccato patterns. You hear scientists building destruction. But the intimate behaviour of movement two, The Bedroom, was harder to plot; and, until the final interrupted threnody arrived, even the approaching mushroom cloud made the musical arguments no tighter. On the sunshine side, the piece showed what a well-rounded orchestral virtuoso Adams can be (as well as a galvanising conductor).

Earlier, after a whiplash Copland Billy the Kid suite, the BBC Symphony Orchestra had been toiling through the whirring mechanisms of Adams’s overextended Century Rolls with the crisply mannered pianist Olli Mustonen. Atomic at least let the instruments loose, from the mournfully gurgling contrabassoon to the desert heat of a solo trumpet, lost in desolation. Music with meat and juice, yes; but still, alas, indigestible.

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