Anna Bolena, Tower of London Festival, London

The showpiece of the first outdoor Tower of London Music Festival, set on an outdoor stage within the castle's outer walls, Anna Bolena ran a few first-night risks: the wind whipped, the cold set the teeth a-chatter. Planes wheeled, buses trundled by. Yet the magic held: rain fell just three minutes after the show ended.

What was striking was how well - especially latterly, with Roger Frith's lighting - this opera came across. True, when the first-rate Philharmonia Orchestra is filtered through monoish speakers, much of the subtlety evades the ear. Gone was much of the detail: you had to settle for a slightly fuzzed sound and a mashing of the upper string tone. Yet the pacing, from ENO stalwart Alex Ingram, was often perfect: it galvanised the drama.

Peter Rice's set, a stylish curvaceous mobile that artfully converted into a prison interior for Act II, served well, controlling the space and providing, by modest gyrations, adjusting areas which Tom Hawkes's restrained moves used to best advantage.

This was Donizetti's first foray with the librettist Felice Romani, and to that may be attributed the brilliant exchanges and ensembles - notably a superb Act II trio - which ensured Anna Bolena acquired enduring popularity. Many of them involve Anne herself; a pity, then, that Hannah Francis started off with such a plummy wide vibrato that the sound emerged like a gloupy gurgle. Later she settled: in the main set-to with Henry she was positively regal; by "ah, segnata e la mia sorte" - "my fate is sealed", the poignancy of her predicament plucked at the heartstrings. The shifting moods of the delirious last scene came over impressively.

Charles Johnston, well-padded, revealed a newfound resonance in lower registers as the unyielding Henry, and Jennifer Johnston took flight in the sympathetic role of Jane Seymour. Tyrone Landau also impressed in the small role of Hervey.

This cunningly planned new festival deserves to become a London fixture.

Festival ends 16 July (0870 895 5666)