MUSIC / Healing a split personality: Anthony Payne on Mehta and the LPO at the South Bank

WITH the ambivalence that he reserved for other revolutionary figures who challenged his identity, Debussy could categorise Berlioz as 'a tremendous humbug who managed to believe in his own hoaxes' while profoundly admiring the lyrical purity of The Childhood of Christ. Although that opinion reveals more about Debussy than about Berlioz, it does probe the earlier composer's individual genius, and any interpreter of Berlioz has to come to terms with both the classical purity and the inventiveness of the hoaxer - or, to interpret Debussy, of the bizarre visionary.

The Symphonie Fantastique presents both sides of Berlioz in brilliant juxtaposition. If a performance is truly to convince, the almost classical grace and detachment of the first and third movements must belong to a world that can encompass the wilder expression of the march and finale. Zubin Mehta in his reading with the London Philharmonic in Tuesday's Festival Hall concert certainly achieved as much, and he drew from his players an interpretation of fire and symphonic concentration as well as of programmatic colour.

In the first movement he drew a pure symphonic line from start to finish while allowing space for a romantically coloured moment or mercurial explosion of energy. The orchestra followed him through his network of tensions with controlled power, placing vital material in bold relief and characterising background detail with point and verve.

The 'Ball Scene' was also delivered with elegance and brio, while the 'Scene in the Fields' painted a picture of calm and grace. Difficult perhaps to create real magic in an acoustic such as the Festival Hall's, but the distant thunder of the drums, combining focus with impressionistic colour, was well managed.

The change of gear into the picturesque glitter of the last two movements was efficiently engineered and the integration of the two parts of the symphony was ensured by not allowing the more outrageous aspects of Berlioz's colouristic requirements to get out of hand. Indeed, the finale's bells were perhaps a little too politely struck, while the 'March to the Scaffold' could have been more brazen.

Berlioz's exquisitely buoyant overture Beatrice and Benedict had opened the concert with much less elan; but after that we heard Andras Schiff in a demonically powered performance of Bartok's Second Piano Concerto. The demands of the outer movements' keyboard textures were met with supreme vitality in Schiff's hammered attack. Yet tone was always radiant, and if the first movement's contrapuntal density in wind and brass had difficulty finding space for itself in the Festval Hall, there was still much to enjoy in the concentration and dynamism of the playing.

The slow movement fared excellently. The coolly mysterious opening and closing sections conjured the stillness of night air, while the humming and whirring of the insect life that seems to interrupt it was superbly dispatched by Schiff and the orchestra. After this the finale danced its way to a jubilant conclusion.