It's still something of a shock to realise that not one of the three major summer productions in Regent's Park is Shakespeare: the superb To Kill A Mocking Bird and late July's The Sound of Music sandwich this dutiful, efficient adaptation of Pride and Prejudice by Simon Reade, first made for the Theatre Royal Bath.

A fair, dry but increasingly chilly evening reduced the likelihood of a "wet shirt" scene for Mr Darcy, though David Oakes makes a good fist of resembling a creepier version of Colin Firth, reinforcing Jane Austen's point that you can't always judge a book by the cover.

The exposition of George Wickham (Barnaby Sax), though, is rather hurried, in letter form, at the top of Act Two, just as the audience is settling down and huddling together for warmth. Indeed, by the end, when things come rapidly to a head, there are so many explanatory letter-reading scenes in Deborah Bruce's production that you could have sub-titled the piece, "Honeymoon Salad, Letters Alone."

Austen's country estates in Herts and Derbyshire are nicely evoked in Max Jones's design, which incorporates wrought iron park gates and a matching green gantry and staircase on a revolve, where the cast convene for the ball-room scenes and, at Pemberley, Darcy's place, freeze like portraits in the entrances.

Most frozen of all (apart from the audience) is Jane Asher's haughty Lady Catherine De Bourgh, who scarcely melts, even in the interview scene with Jennifer Kirby's delightful Elizabeth Bennet, which she plays like Lady Bracknell grilling Jack Worthing.

Elizabeth and Darcy are the cleverest people in the novel, and that always translates into a good Beatrice and Benedick double-act on stage, while the verbal interjections of Frances McNamee's Caroline Bingley in gold satin sharpens into bitchiness, and the resigned commentary of Timothy Walker's hilariously light-footed and carefully articulated Mr Bennet soften the blows of disappointment.

Walker makes a great deal of a tedious role, and there are outstanding performances, too, from Ed Birch as the unctuous heir to the estate, Mr Collins, a spidery cleric with a sneer trying to smile, and from Rob Heaps as a sweet-natured, hesitant Mr Bingley whose arrival at nearby Netherfield Hall sparks the campaign of marrying off the five girls.

The coarse-grained Mrs Bennet, whom Alison Steadman once dangerously transformed into a Mike Leigh harridan, is played with imperishable bumptiousness by Rebecca Lacey, though you'd never really credit her with the famous opening line which the demands of third-person narrative consign to her here.

Lillian Henley's pastiche period music would be more interesting if played live, not blared through speakers, a fault highlighted by the fact that at least three of the girls on stage play the piano quite decently. Tina MacHugh's lighting is a key element, but this is a production that neither says anything brilliant or new about Austen nor benefits, really, from being played in the open air under a darkening sky.