Maxwell Davies double-bill Cheltenham Festival

Mary Thomas, who died this year, was a towering figure of British music theatre over three decades. Fittingly, the Cheltenham debut of the new music group Psappha was dedicated to her memory in a few pertinent opening words from Sir Peter Maxwell Davies. Doubly apt because, of the two stage works paired in this Davies double-bill, one, the 1974 monodrama Miss Donnithorne's Maggot, had become virtually her calling-card.

She and Davies's own ensemble, The Fires of London, which set new music ablaze in the Sixties, have worthy successors in Psappha. Indeed, just how well Miss Donnithorne - like its precursor, Eight Songs for a Mad King, a tale of individual isolation, crushed freedom, imploding optimism and madness - has stayed the course could not have been made clearer.

Tom Yang's dance-reading of Vesalii Icones in the first half showed dedication, but lacked focus. The early part - done usefully in the round, if at the cost of sightlines - gained poise from a pleasingly responsive, uncreaky floor; his tableaux (based on Andreas Vesalius's gallows drawings) were evocatively precise, his danced build-up to them less so. Odd tasselled garb distracted the eye; the crucial disrobing was needlessly clumsy. Nimble anklework and facial subtleties made some amends, but Yang's end remained an inexplicable puzzle: the final, iconoclastic blasphemy has a blunted impact if no recognisably sacred image has been built in the first place.

Much hinged on Jennifer Langridge's beautifully judged, fast-maturing playing of the cello solo role - a kind of pure alter ego complementing the dancer. Psappha's acuity of individual performance and perceptive ensemble paid countless dividends. Conductor Paul MacAlindin brought that simple clarity of beat and half beat, measured command of score and assured coaxing of crucial leads, to generate total confidence.

No one benefited more than Emma Turnbull, Psappha's splendid young soprano playing Miss Donnithorne. A jilted Miss Havisham figure, ensconced amid mouldering wedding-cake, she railed, yearned and pouted her way through Randolph Stow's disconcertingly believable text. This was a powerful dramatic presence, cogent and pathos-ridden. It recalled Josephine Barstow in the way Turnbull managed to turn the most taxing, angular lines into almost a form of Lied.

Psappha matched her at every point, from magical flute and marimba duet to the uncanny mind-warp of clicking metronomes and netherworld of crepuscular echoes as the soloist circled the hapless conductor. MacAlindin's restrained accompaniment of those cadential moments in which she took momentary hapless flight (over evocatively subliminal percussion) was a key to the second half's palpable success. Festival continues to 20 July (01242 227979)

Roderic Dunnett