If anybody deserves a Nobel Prize for Peace, it is surely Daniel Barenboim. The West-Eastern Divan Orchestra he founded with Edward Said in 1999 brought young Arab and Israeli musicians together to the extent that they actually share desks.

Since then their concert venues have included Ramallah, the first time many of the youngsters had encountered the reality of the Palestinian settlements.

The orchestra has been preparing for last night's Prom at a summer camp near Seville. As usual the two-week session has been about creating social and political harmony as much as musical, but this concert brought home just how meticulous Barenboim's coaching is. This is now a first-class orchestra by any standards, and its members play with a unanimity of purpose that is as moving as it is impressive.

The programme was a tough one: Schoenberg's taxing Variations for Orchestra and Brahms's challenging Fourth Symphony, with the Haydn Sinfonia Concertante in B Flat Major for oboe, bassoon, violin and cello (the soloists taken from the orchestra's own ranks) thrown in for good measure.

The orchestra has grown in size. It began as an ensemble of about 70 players; for this tour there are 120, ranging in age from 12 to 30, and they come from not just Israel and Palestine but also Jordan, Lebanon, Egypt, Syria and Iran.

But there is also a massive development in musical standards since those early days. When the orchestra began, there were inexperienced youngsters playing third-world instruments. Now there are three members who also play with the world-renowned Berlin Philharmonic.

In the Brahms the extraordinary cohesiveness of the ensemble allowed Barenboim to fashion a reading of wonderful-rhythmic flexibility. The Schoenberg-by contrast, highlights individual instruments and here one could admire the soloistic skills and their combination in intricate but scrupulously balanced textures.

The late-night Prom was notable for the star billing of Patrice Chéreau in Stravinsky's Soldier's Tale.

Known chiefly as an opera director and film-maker, Chéreau is also a brilliant actor, and here he took the parts of narrator, soldier and devil, sweeping through the French text with natural fluency, acting out the story as far as possible. It's a nonsense, of course, to have acres of spoken text delivered in a foreign language - it was impossible to follow both the translation and the stage actions - but the presence of Chéreau almost made it forgivable.