London Sinfonietta / Knussen, Queen Elizabeth Hall<br/> BBC SO / Honeck, Barbican, London

There was music by Hans Werner Henze in both these concerts. Under Oliver Knussen, the London Sinfonietta offered Kammerkonzert 05, the latest of several revisions to his First Symphony of 1947. An awkward combination of Hindemithian earnestness, some rewardingly unforced lyricism and a little naughty avant-gardism for that post-Second-World-War fresh start, it makes a peculiarly ambiguous statement. But the slow second movement had Paul Silverthorne's solo viola nicely to the fore, and the Sinfonietta played vividly and intelligently.

Under Manfred Honeck, the BBC Symphony Orchestra offered Scorribanda sinfonica: a more extensive reworking of a "dance drama" that Henze wrote in 1956. With most of the original 1950s dance references removed, however, this retread relies mainly on some engaging, if dense, writing for large orchestra.

Fortunately, each of these concerts contained at least one much more stimulating musical experience. In the case of the London Sinfonietta, it was Mauricio Kagel's Kammersymphonie, which turned out to be an arrangement of his 1973 composition entitled 1898. The original is a sort of spoof reconstruction of early recorded sound, to celebrate the 75th birthday of the DG record company. This revision is more subtle in its quirkiness, but its lean and mean counterpoint still teems with inventive touches and occasional sheer craziness. I loved it.

With the BBC SO, it was the Brazilian pianist Nelson Freire's account of Beet-hoven's Fourth Piano Concerto - a fresh, stimulating performance of a classical masterwork. Freire's platform manner is so undemonstrative that he would look boring on a video without the sound, and he took fastish speeds to which he kept with an avoidance of rubato that risked becoming relentless. Yet his playing was so full of character that it was riveting. Here, and in an impressive Tchaikovsky Fifth Symphony, Honeck persuaded the BBC SO to punch well above its usual weight.