THEATRE / Big armchair theatre: Paul Taylor on The Day after Tomorrow at the Cottesloe and the revival of The Old Country at Watford

As we emerged from The Day after Tomorrow (the new play for children at the the Cottesloe which focuses on sibling rivalry and ways to rise above it) I asked my five-year-old daughter if the story (involving two squabbling girls) had made her think any differently about her own three-year-old sister. 'Not a lot. You see,' she added seriously, 'Bee really is a pest.' So much for art's fabled power to alter our perceptions.

With its arresting design by Kate Burnett, the 55-minute show certainly offers you a different perspective on armchairs. A gigantic, roomy version of one dominates the stage, hung about with a woolly landscape-picture that falls in curving folds from the two crossed knitting needles that surmount the scene. Beguilingly, the armchair is used to symbolise all the various locations. Covered with a dust sheet, it becomes the mountain the sisters have to climb; swivelled round, with its twisty innards exposed and lengths of leafy netting strung across its back, it turns into the confusing depths of the forest. Equipped with a little chimney and concealed drawers and holes, it mostly represents the home of the heroines - Alice (Vicki Pepperdine), the smug, bossy older girl and Jenny (Kate Somerby), her put-upon, but more daring (and more trying) younger sister.

The adventures in Roel Adam's play start with the appearance of mysterious presents and then of a still-to-be-born baby brother (Sally Martin). Though not yet nought years old, this creature saws away at a violin in a virtuosic manner that must be a little galling for the comparative wrinklies in the audience (like my daughter) whose struggles with a stringed instrument are still, in every sense, less harmonious. The sibling baby reveals that, before he can be born, he will have to be rescued from the seductive tyranny of Music and that, to achieve this, his rescuers must seek him out from a door in a forest over the horizon.

As parents quickly learn, the paradigmatic story of sibling-rivalry-resolved in children's literature presents a situation in which, on some jaunt or other, the mischievous bossed-about younger child either gets lost or hides from the domineering senior. Classically, he or she then witnesses the older sibling weeping with sorrow and guilt, a spectacle that is supposed to bring home to the child how being the older one isn't as enviable a position as he'd imagined, and both come to realise how much they actually love each other. A variant on this happens here, though with the interesting twist that providence (in the shape of a witch and a fairy) manoeuvres the girls into a reunion where they don't at first recognise one another and so interact with a freshness revealingly free from the old prejudices.

In Anthony Clark's production, the adult actors playing children give appealing and unpatronising performances (good that the smaller, junior girl is allowed in other respects to be the more mature) and there are some fetching routines, such as the baby's comic response on the violin to the various names they suggest for him. I just wish I could recommend the piece more warmly. It has undoubted merits but they are served up with a well-meaning middle-class wholesomeness that makes you (all right, me) itch to deface something. My daughter certainly liked the show, but we had to agree that it wasn't a patch on the stage version of Roald Dahl's The Witches, as unimproving a work as a child could hope to encounter.

To Adam's heroines, home is an armchair; to the defected English traitor in Alan Bennett's The Old Country (revived now by Roger Smith at the Palace, Watford), home is wherever he's not wanted. In other words, he's more at home feeling not at home in Russian exile than he would be back in the England whose decline he elegises from afar. This becomes apparent when moves are made to repatriate him. Oliver Ford Davies brings a less textured embitteredness to the character's flights of donnish pastiche and weevilled whimsy than Alec Guinness, who created the part in 1977. But his clerical manner darkens admirably towards the end. As Duff, the brother-in-law despatched to secure his return, Edward da Souza gives a beautifully comic performance, oozing the plummy self- satisfaction of one of the Great and not-so Good.

The production has its workmanlike patches, but Bennett's 'Home Thoughts from Abroad' on the nature of belonging and of Englishness still emerge as profound and profoundly entertaining. One line has noticeably dated: 'Is there anyone not embarrassed? The Queen perhaps' - a speculation now greeted with audible lese-majeste.

(Photograph omitted)

The Day after Tomorrow: in rep at the National Theatre (071-928 2252).

The Old Country: Watford Palace (0923 25671) to 23 Feb