Even before last Wednesday's world premiere of her first work for the City of Birmingham Symphony Orchestra in her role as "Composer in Association", Judith Weir has proved a benevolent presence in the city. Last March, her instrumental work Musicians Wrestle Everywhere was premiered by the Birmingham Contemporary Music Group, and in their new season Weir has been providing articulate, commendably jargon-free introductions to selected pieces. Her new composition for CBSO raises expectations.

The decision to prelude Forest with Vaughan Williams's Fantasia on a Theme by Thomas Tallis was both wise and witty. Rattle and the CBSO have seemed a touch wary in coming to terms with this most English of composers, but a memorable reading of the Fifth Symphony last year showed that they have considerable affinity with his style. If the sight of Rattle plunging headlong into the Sea Symphony is a spectacle unlikely to be realised in the near future, his way with the nearly contemporary Tallis Fantasia suggests strongly that early Vaughan Williams could be him.

This was a superbly dramatic performance which nevertheless managed to generate an air of mystic contemplation. A good part of the latter was supplied by Symphony Hall's acoustic chambers which, wide open, gave the kind of "sustaining pedal" ambience common in the best English cathedrals. While the acoustic of the building kept Vaughan Williams's textures vibrating in the air, the strings provided a balance between precisely placed chords, unanimous rubato and passionate solos.

The wit in placing the Fantasia before Judith Weir's Forest was that the new work seemed rooted in the same mulch as the Vaughan Williams. Growing out of some consonant string solos, Weir's piece gave glimpses of the elemental qualities that draw together such places of contemplation as forests and cathedrals. As always with first performances, it is tempting to plunge into a maze of references to other composers in order to give an impression of the new work's sound-world. High on my list was Tippett's A Midsummer Marriage, but perhaps more fundamental to its phylogeny was the organic growth of Sibelius. Underlying the detail, all of which was ear-catching and grateful, was a sense of deeper structure. That it did not quite arrive by the end echoed the composer's own feeling that Forest is the introduction to a much longer work.

Those who take the view that Das Lied von der Erde with a baritone rather than a contralto is a bit like strawberries without the cream should have been present on Wednesday night. I felt some sympathy with these sybarites in the early songs, but in the massive final "Abschied" all doubts melted away. Part of the problem for Thomas Hampson and John Mitchinson, gallantly standing in for an indisposed Peter Seiffert, was that the orchestra was on a bit of a spree. With the cathedral haze that had benefited Vaughan Williams removed, the players opted for super-real clarity. This meant lots of marvellous detail, but it was delivered with a verve that often submerged the singers.

"Der Abschied" was a different matter. Hampson floated his tone with a delicacy that would have made the most distinguished contralto proud. Like a solution solidifying around a seed crystal, Rattle and the orchestra supported and ornamented a deeply touching account of this most deeply touching of songs.