Jane Austen's Emma is the maiden show from Thistledown Theatre, a new drama venture in Oxford, attended by a numerous audience swelled by a large contingent from d'Overbroeck's College. This is of course a costume drama par excellence, the story known to generations of school and college students, as Miss Austen probes the intricacies of the British class system and the ways of the human heart, as several of the characters - and not least Emma herself - come better to understand their own selves.

The choice of St Mary the Virgin Church as venue is a bold one and not without its challenges: the surrounding surfaces are invariably hard, the acoustics echoing and the actual playing space was quite a cramped, raised platform surrounded by the black and white stone tiles of the transept floor. The basic sight line of the audience is a problem, too, given that there's no rake to the ground floor seating - making it tricky to venture forth from the platform onto the lower surrounds. This made the director Laurence Goodwin's blocking of the players seem occasionally a little stilted as they strung themselves across the dais, and free movement was sometimes at a bit of a premium.

If this novel is to be turned from pure conversation piece into if not red- then pink-blooded drama, then the twin plot-strands involving the machinations of Emma herself and the revealed status of Jane Fairfax have to acquire a resonance that engages the audience's attention. Jane in the novel is to my mind a rather shadowy alter ego to Emma, but here she's an entirely peripheral figure, much talked of but little seen and then all but mute. This creates something of a void near the heart of the tale, and it's to the considerable credit of Sarah Pyper as Emma that her calm but strong persona almost compensates for the absence of this intended duopoly.

The staging of the key picnic scene at Box Hill left a little to be desired, key in that it marks Emma's descent from thoughtlessness and delusion vis a vis both herself and other people into nastiness towards the irritating but essentially harmless Miss Bates (Liz Hutchinson). The put-down lacked clarity, although Ms Hutchinson did very well in this difficult part, finding more than a bit of dignity underneath the babbling stream of consciousness. I also liked Simon Marie as an ebullient Frank Churchill. David Guthrie, a dead ringer for Humpty Dumpty, was a peevish Mr Woodhouse, and Adi Himpson had a decent stab at the Molieresque 'raisonneur' Mr Knightley, but I wondered whether he and the excellent Julian Fox, underused as Mr Weston, might with advantage have swapped roles. Ida Persson brought energy to the role of the self-important Mrs Elton, at one time laughing so hard I thought she would burst.

The play was greatly enhanced by authentic period costumes and slick lighting design. In the end, this production stand or falls on its Emma, a long and taxing role since the character here is not only protagonist but also narrator. Sarah Pyper got the tricky balance just right between Emma's youthful gaiety and patronising do-goodery. Her failure to grasp the nature of her own heart and her wrong-headed matchmaking are entirely convincing. She quietly dominates the stage both vocally and with fluent movement.

The show continues until 13th August. Recommended as civilised, thoughtful entertainment; a strong start from Thistledown Theatre.