Orchestra of the Swan, an up-and-coming Stratford-based chamber ensemble, are planning a major celebration of the Michael Tippett centenary next year - but right now their artistic director David Curtis has embarked upon a series that includes composers who shared Tippett's ideals.

Like Tippett, Robert Simpson was a life-long pacifist, and uncomproming in his principles, as the tenor of much of his Seventh Symphony rather underlines. This single movement work was conceived to be heard in recording, as a one-to-one experience, not in public performance. The Pittville Pump Room was intimate enough to offer a valid compromise here.

While it was the work's central adagio section that spoke most directly, an almost imperceptible transition to the motor energy of the final allegro allowed the building of real tension, making the sheer desolation of the end - with its single pitch sustained like a siren - all the more unsettling. All credit then to Curtis and the Orchestra of the Swan for a performance of such sterling commitment.

They flanked the Simpson symphony with two classical works, the first being Mozart's Paris Symphony, K297, with its elegantly lucid andante and lively finale. After the interval, the Indian pianist Fali Pavri was the soloist in Beethoven's Fourth Piano Concerto.

The slow movement's alternation of calmly reasoned statements from the solo piano with the more strident responses of orchestra has long been interpreted as a reflection of the power of the individual to influence the mass. Here, it made for a strong parallel with Simpson's belief in the need for the voice of reason to make itself heard. Parvi's expressive phrasing and the gradual acquiescence of the Swan strings eloquently reinforced the point.