Even Beethoven's reputation might dip if all his music was crammed into three days. That's presumably why, after 21 years, the BBC Symphony Orchestra is ending its tradition of devoting one weekend each January to performances, talks and films about one composer.

But at least the final victim proved gloriously fit for purpose. I thought I could pigeonhole Judith Weir's music as being translucently orchestrated, imbued with folk inflections from East and West (or rather North, since her Scottish ancestry is always lurking in the mix) and deft at bringing out wry ironies in the tales she selects as subjects.

So it is. And it's wrought in a quirkily tonal language that is accessible without ever being cheesy. But her work is also much more varied in its mood and resources than I had realised.

There's a creepy darkness, for instance - a feeling of intangible evil in the air - running through her 1990 opera The Vanishing Bridegroom. That was given an atmospheric concert performance on Saturday under Martyn Brabbins's direction, with Jonathan Lemalu outstanding in the sinister roles. Weir arranges her material - three Scottish folk tales - to convey a sense of the same archetypal figures caught in a recurring cycle of temptation and doom, broken only after an epic confrontation between a young woman and the Devil.

That confrontation is reminiscent of the graveyard scene in The Rake's Progress, which is fitting since Weir's pithily sardonic style here often evokes Stravinsky's score. But she is clever enough to leave layers of Henry James-style ambiguity, conveyed by stunning interludes. The air of mystery was deepened on Saturday, it must be said, by the breakdown of the surtitles. Even so, it's high time that The Vanishing Bridegroom reappeared on a British stage.

Friday's main concert had entertaining folk contributions from the English Acoustic Collective, the Scottish concertina virtuoso Simon Thoumire and jazz pianist David Milligan. But under André de Ridder's baton it also included four of Weir's most characterful orchestral works: the shimmering Forest; the subtly paced song-cycle Natural History (Ailish Tynan a rapturous soloist); the sombre-hued but surprisingly wild orchestral showpiece Winter Song; and the lovely Welcome Arrival of Rain, in which Bollywood-style melodies flirt with minimalist riffs.

Finally, on Sunday, came Weir's new, 25-minute choral and orchestral piece, CONCRETE. It's a musical excavation of London, using texts ranging from Evelyn's eyewitness account of the Great Fire to a litany of patron saints for City churches, and evoking a place of transients and transience, forever being burnt, blitzed, bulldozed and remade. I liked the non-ending - a typical Weir touch, suggesting that the music, like the city, is a constant work-in-progress. But I found the prosaic choral writing and stilted narration (delivered by Samuel West) uninspired. Pity. Otherwise it was a revelatory weekend.

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