The King'S Consort, Wigmore Hall, London

It is easy to see why this period band - led by their founder Robert King, who's as happy chatting with the audience as he is skipping between organ and harpsichord - are perennial Wigmore favourites. They're young and agreeably international, and several members have carved out independent niches as musicological authorities. As their massive discography confirms, they bring freshness and curiosity to everything they touch, and they play with total conviction.

They turned the first half of this all-Vivaldi programme into an ear-opening experience, with three works that must have been unfamiliar even to the Wigmore's cultivated clientele. First came the Concerto for Viola d'amore (RV 396), and how nice it was to make proper acquaintance with this now-rare instrument. Bigger than the modern viola, but with a silvery sound like that of the viol, it lets you sense both the hair of the bow, and the delicate harmonics of its supernumerary strings. Unclouded by thick ensemble textures, Dorothea Vogel's gracefully-managed solo flights suggested why Bach was later to find Vivaldi's music so captivating; each short movement was a perfectly-shaped line of thought.

In the solemnly playful Concerto for Cello (RV 417) we were reminded of the gulf between the Baroque and the "classical" variants of that instrument, as Jonathan Cohen showed what effects could be achieved without benefit of the latter's lush, luxuriant timbre.

Then came a really rare combination of instruments, with the Concerto for Viola d'amore and Lute (RV 540). I wondered whether I would hear the lute at all from my critic's seat at the back of the stalls, but thanks to the Wigmore's acoustic and Vivaldi's musical tact - letting the soloists duet with the lightest ensemble accompaniment - I was able to savour the fey charm of this unique pairing.

By rounding things off with The Four Seasons, the band left itself no hiding place. The challenge was not that the work is overperformed, but that we all carry recorded versions in our heads, and our expectations of the soloist are unrealistically high. Moreover, Simon Jones was not playing a Strad but a harder-to-manage Baroque violin, and at times went teeth-gratingly off key. The ensemble playing was occasionally rough at the edges, and the evocations didn't always work - "Summer" wasn't suffocating enough, and the viola's barking dog drowned out everything around.

But we got wonderful moments too, notably in the frozen blasts of "Winter", and in the "Autumn" adagio, where the harpsichord arpeggios wander against a backdrop of serene string sound. By the encore - the "rain" section of "Winter" - both Jones and his colleagues had got things perfectly sorted, and we all went out on a high.