In the concert hall, the beginning and end of Wagner's Tristan und Isolde are regularly elided, so that the prelude to the first act is followed by the Liebestod that Isolde sings over her dead lover before expiring herself at the final curtain. But David Robertson's performance at the start of his concert with the BBC Symphony Orchestra - his first appearance as the orchestra's principal guest conductor - provided a very different kind of elision. As the final note of the Tristan prelude died away, the orchestra moved not into the hushed opening of the Liebestod but entered the tremulous, unstable world of Schoenberg's Erwartung, the monodrama completed in 1909 that represents the climax of musical expressionism.

So half a century of music history was short-circuited, for the undermining of tonality that began with the unresolved chords of the Tristan prelude led inexorably to the atonality of Schoenberg's expressionist pieces. Dramatically and musically it worked perfectly here, for Erwartung is also a kind of Liebestod, as the unnamed female protagonist searches for her lover in a nightmare world that may be real but is more likely the product of her own fears and guilt. The soprano role was sung wonderfully by Susan Bullock, with the expressive warmth, accuracy and dramatic intensity it needs but so rarely gets, while Robertson ensured that the detail packed into every bar of the orchestral score was perfectly distinct and headily potent.

After all that unresolved longing, Beethoven's Fifth Symphony provided resolution and assurance in the second half of the concert. Not that Robertson's performance lacked in tension or drama - he launched the first movement at a formidable pace, and maintained that intensity through the four movements in a seamless arc. Altogether, a fascinating piece of programming.