MUSICAL A White House Cantata City of London Festival, Barbican, London

How often do you get to hear the world premiere of a musical by the late Leonard Bernstein. A celebration of the first 100 years of the White House seen through the eyes of generations of black servants, 1600 Pennsylvania Avenue is the one that got away. It opened in 1976, folded seven days later and was never recorded. Here was the first opportunity to hear it shorn of its schematic book, the score reassembled from the piles of excisions and revisions of the original benighted try-outs and Broadway run, and retitled A White House Cantata.

And what a score it is. Bernstein himself raided it for later works and the radiant opening prelude resurfaced as the eloquent Walt Whitman setting in his magnificent orchestral cycle Songfest. Much of the musical material is laid out in the opening number, where President George Washington and Congress choose a location for the new capital. The musical heart comes two numbers later when Abigail Adams and Young Lud, the son of a slave, sing "Take Care of the House". The melody climbs and curls back on itself, a gently rocking hymn of husbandry and gentle optimism.

The shape of that yearning melodic line, inverted or reworked, reappears with increasing pathos, most notably in the questing, hopeful, night-time duet between James and Eliza Monroe, "The Mark of a Man". It is one of many high-water marks in an endlessly inventive score that runs to a splendid march, a comedy scene of the British invasion of 1812 complete with sonatina and drinking song, barber shop-style choruses, and an adaptation of "The Star Spangled Banner".

On paper, it looked like a winner. The performance, however, was quite another matter. This wasn't a concert, this was "an event", with an international cast, lighting effects and huge forces. Which is where the problems began. Why use what looked and sounded like virtually the entire LSO? The original pit band cannot have boasted all those strings, let alone 13 wind players. As a result, the operatic voices had to be amplified with a bewildering array of radio, hand-held and suspended microphones, and the result was loud, overblown and muddy. Thank heavens someone had the foresight to print Alan Jay Lerner's taut and often witty lyrics in the programme. But, although we could read them, you searched in vain for the name of the director. Given the poorly rehearsed, sloppy staging, I'm not surprised.

Even if Kent Nagano had wanted to mould and shape the singing, it proved impossible with the chorus flung to either side of the stage and most of the soloists standing well beyond his eye-line. His inflexible, four- square conducting proved he wasn't a natural for this material. Dietrich Henschel sang all the Presidents with his rich baritone, but why choose a German singer for this all-American piece? Nancy Gustafson's singing of the Presidents' wives was adequate but she hadn't learnt the role, thus adding to the rehearsal-like atmosphere. She certainly couldn't lift the show-stopping "Duet for One". Patricia Routledge, who created the role, was in the audience. What she made of it, I can't imagine. As for the embarrassing acting and accents of the minstrel scene, it made Dick Van Dyke's work in Mary Poppins look masterly.

The committed singing of Thomas Young and Jacqueline Miura as the servants stood head and shoulders above the rest. It was impossible to believe that their climactic duet "This Time" was cut from the original show. The sooner someone herds them and, say, Thomas Hampson, Dawn Upshaw and Michael Tilson Thomas into a recording studio, the better. David Benedict