Alone it Stands, Duchess, London<br></br>The Lieutenant of Inishmore, Barbican Pit, London

Rugger-buggers are no match for the kitty-killers of Ireland

A Labrador puppy with a rugby ball in his furry little mouth gazes beseechingly from hoardings outside the Duchess. This is to promote, no, not toilet paper, but the first West End show to open in 2002. I regard this as an inauspicious start since I'm neither a pooch-fancier nor a rugger-lover. To be fair, the tag line holds some appeal: "The day the underdog bit back". And for sure, Alone It Stands is an accessible and affable comedy from Ireland which re-enacts a miraculous victory of the David vs Goliath variety.

In 1978, the world's burliest, scariest rugby team – the New Zealand All Blacks – were pounding their way across the British Isles, beating everyone. Only in backwater Limerick, the unfancied lads of Munster jogged on to the pitch and defeated the Kiwi giants. With a final score of 12-0, the smalltimers became living legends.

This show, in itself, is a little guys' success story. Written and directed by John Breen for a Co Mayo troupe called Yew Tree, Alone It Stands was initially performed in a handful of rugby clubs. Then it landed warm reviews on the Edinburgh Fringe and now it's scored big time – picked up by Andrew Lloyd Webber's Really Useful theatres group which was, of course, behind the maestro's Ulster soccer musical, The Beautiful Game.

Breen's staging is simple, with a gym mat representing the field and Munster's modest skyline for a backdrop. His cast of six – including one sturdy actress, Niamh McGrath – are game for a laugh, juggling half-a-dozen roles each. Neat choreography means the All Blacks' preliminary Maori stomp melds into a scrum, and awesome sprints are mimicked in slow motion with amusingly strained faces.

The actors supply the commentary as they pass the imaginary ball, and glimpses of the wider communal picture are interwoven. Our sporting heroes morph into jostling fans – with one pessimist harping on Ireland's history of losing military battles. McGrath is also lifted above the men to portray one of the player's wives, struggling through childbirth without her man by her side.

Really though, Breen only superficially grapples with Irish socio-political worries. Mild laughs rule the day. This is hardly breathtakingly original physical theatre either. Alone It Stands echoes John Godber's Up 'n' Under, with less verbal vibrancy. As some of the role-swapping is fuzzy, it also seems a poor cousin of Stones in His Pockets, the recent West End hit by Ireland's Marie Jones. Dire attempts at Kiwi accents and corny impersonations of kids and pets don't help.This show looks like stop-gap programming to me.

Though certainly not for the squeamish, The Lieutenant of Inishmore by Martin McDonagh is a far blacker and better comedy about Irish paramilitaries' mad internecine battles. You have to admire the RSC for having the nerve – and sufficient buckets of gore – to premiere this satire (transferred from Stratford) which rips the mickey out of murderous terrorists and which could, equally, have the Animal Rights brigade going ballistic: McDonagh's beyond-Ortonesque farce entails fluffy moggies being blown to kingdom come (albeit only in make-believe).

An INLA extremist called Padraic (chatty, psychotic David Wilmot) is busy pulling the toe nails off a drug dealer when his old da, Donny (Trevor Cooper resembling a nervous ogre), rings from the Aran Islands to report our Padraic's beloved pussycat is the worse for wear. Human heads are going to roll indiscriminately for this – with confusions about the kitty-killers and a romance with a rifle-brandishing lass en route.

McDonagh's shock tactics may feel adolescent occasionally, but he sharply lambasts a culture that casually mingles sentimentality and brutality. His grotesque vision of idiotic massacres – executed in the name of national ideals – has a Swiftian ferocity. Wilson Milam's production deftly balances surreal nuttiness with naturalism: outrageously funny and, sometimes, harrowingly grim.

k.bassett@independent.co.uk

'Alone It Stands': Duchess, London WC2 (020 7494 5075), to 9 Feb; 'The Lieutenant of Inishmore': Barbican Pit, London EC2 (020 7638 8891), to 23 Feb