John Donnelly's new version of Chekhov's The Seagull for the English touring company, Headlong, succeeds precisely where the same company's Medea failed last year.

Whereas Mike Bartlett's modernisation of Euripides was clunky and bathetic, Donnelly has written a beautiful, vital, fluid script which reinvigorates the work of an author not always well served by British reverence.

Not for Donnelly nor director Blanche McIntyre the ossified orthodoxy of many British Chekhovs. This is no "faithfully" languid costume drama, replete with masochistic celebrations of moral defeat and sexual failure. Rather, Donnelly captures brilliantly the living essence of the play, precisely by departing from the word.

One need not strain for comparisons between Czarist Russia and austerity-wracked, contemporary Britain (and, thankfully, Donnelly does not). It is enough that Laura Hopkins's superb minimalist stage (which is dominated by a wonderfully versatile wood-and-metal device which is, by turns, a bench, a see-saw, and a dinner table) plays host to a real drama of social uncertainty, aesthetic debate and ungovernable sexual desires.

It is as if, in cutting away at the accumulated layers of British rep guff which have grown over Chekhov, Donnelly has revealed the play, not as a work of comfortable realism, but as a disquieting tragedy worthy of the Ancients. When teenage actress Nina (Pearl Chanda, shining in a universally excellent cast) returns from Moscow, broken by her continuing love for the emotionally brutalist poet Boris Trigorin, she appears as tragically powerless as any Attic character.

Abigail Cruttenden's marvellous Arkadina is typically outrageous in her thespian ego, but so much more intelligent and self-aware than she's often given credit for. The scene in which Gyuri Sarossy's Trigorin begs Arkadina (his lover) to be allowed to bed Nina under a pretext of high art and free love is an absolute gem. Arkadina, an actress of considerable sexual power, has him reduced to adolescent masturbation in a trice.

This is Chekhov freed gloriously from the constraints of more than a century of well-intentioned reverence. If educationalists can swallow the occasional expletives, Donnelly's text should become the standard one in British schools.

If Headlong are welcome visitors at the Citz, the National Theatre of Scotland's latest children's show – a promenade piece based upon Neil Gaiman and Dave McKean's acclaimed picture book, The Day I Swapped My Dad For Two Goldfish – made itself very much at home when it began its tour at Greenock's recently opened Beacon Arts Centre (a superb venue, situated perfectly on the south bank of the Clyde estuary). As self-proclaimed genius Neil and his crazy little sister try to recover their Dad (whom Neil has exchanged for the titular aquatic pets), Lu Kemp's fabulously off-the-wall production wends its way through the backstage areas of the theatre.

From the very outset, the play (which is aimed at children aged six and over) is an uproariously funny adventure. Swapping proves infectious, and everywhere Neil and his sibling go, they find that their father has been exchanged for something else, be it an electric guitar or a big, white rabbit named Galveston.

Our travels to meet a series of brilliantly observed characters in gloriously designed houses are rendered all the more colourful by great live music and song. Laurie Brown and Veronica Leer are tremendously engaging as the squabbling siblings in hot pursuit of their missing Dad, while Antony Strachan and Rosalind Sydney are deliciously frantic in the vast array of supporting roles. Indeed, Strachan (a heavyset bloke with a serious beard) provides the comic highlight when, donning huge pink-rimmed spectacles, he makes his hilariously camp-yet-sinister appearance as Vashti, the mad girl who swapped Dad for a gorilla mask.

Ending with a post-show swap shop (from which Noel Edmonds and Keith Chegwin are, mercifully, absent), Kemp's highly inventive, technically accomplished production is a great credit to the NTS.

For tour details of The Day I Swapped My Dad For Two Goldfish, visit www.national theatrescotland.com