On paper, the programming looked bizarre: Mozart, Wagner, Stravinsky and Richard Strauss. A little bit of everything. But that was before any contribution by the London Philharmonic Orchestra under their star catch for the evening, Mark Elder, plus the realisation that the entire programme was chamber music writ large.

A full house had turned out to welcome Elder (who was escaping the last performance of Il barbiere di Siviglia at the Royal Opera House). The conductor has been producing wonders up north with the Hallé, and here was to be seen working wonders down south. And in what good heart the LPO appears to be, despite the awfulness of their circumstances with regards to their residential home, the scaffolding-swathed Festival Hall.

And the programming turned out to be so subtle. Mozart's 34th symphony in its original version (without flutes), the oboes and bassoons placed under Elder's nose with "period" horns and trumpets at the back. What a marvellous sound. Elder, in the first movement, so judiciously underlined Mozart's "flicking" between major and minor, in the slow movement - essentially, strings with unobtrusive bassoon doubling bass - so carefully regulated string vibrato, with Andante di molto read as "keep moving".

Anna Larsson was the statuesque contralto in Hans Werner Henze's 1979 chamber orchestration of Wagner's piano version of the five Wesendonck Lieder. Larsson has the richest of deep-coloured voices, which, particularly in "Schmerzen", was extraordinary to hear. Performing without a score, her delivery was compelling, but Henze's instrumentation provides something of a challenge to the soloist. The sounds of muted horns, alto flute, double-bassoon, harp, kept drawing my attention to the scoring rather than the piece. But totally fascinating, no doubt.

Then came the tightest of performances of Dumbarton Oaks, Stravinsky's "wrong-note" Bach chamber concerto. What elegance, spice and freshness (particularly from the clarinet), showing that the spirit of Pulcinella was not forgotten.

And to end, Richard Strauss's Metamorphosen for 23 solo strings, the LPO violins and violas standing to play. It is hard to believe that it was written in 1945, almost 10 years after the Stravinsky. It is Strauss's gigantic lament for the loss of German culture, with Beethoven's Eroica funeral march embedded in the swaying and swelling texture. Elder, so fine a conductor of Elgar, seemed, touchingly, to draw the spirit of these two lamenting composers together. An exceptional evening.