The Lion in Winter, Theatre Royal Haymarket, London Juno and the Paycock, NT Lyttelton, London Reasons to be Pretty, Almeida, London

The lead actor does a sterling job with shoddy goods. But what's happened to Nunn's quality control?

Is he still the king of beasts when nipped by frost?

In James Goldman's lightweight history play The Lion in Winter – premiered on Broadway in 1966 and now revived by Trevor Nunn – Robert Lindsay's Henry II of England is past his prime. He still holds sway with cloak-swishing suavity, cat-and-mouse games, and occasional angry roars. However, he is facing an awfully inclement family Christmas.

His scheming sons include the bellicose mummy's boy Richard the Lionheart. Henry is wary of divvying up his empire which, through his marriage to Eleanor of Aquitaine, extends to the Pyrenees. In this conflation of 12th-century spats, his castle is rife with further machinations as, gathered under one roof, we also have Joanna Lumley's long-imprisoned Eleanor (determined to get her own back); Henry's mistress (officially Richard's fiancée); and the French king (revealed as Richard's ex-squeeze in a caught-in-the-closet scene that aspires to farce).

Alas, The Lion in Winter is a major letdown, somewhere between pseudo-Shakespearean drama and lame sitcom. Sure, Goldman's script offers some droll quips, but with reams of tosh in between. ("The hot wine steams, the yule log roars, and we're the fat that's in the fire" etc.) It has half a mind to wax serious, routinely flips back into bathos, generates no suspense. Would that Lindsay – a magnetic actor, now free from BBC1's My Family – had a better play than this to grapple with. He's doing a sterling job with shoddy goods, displaying ace comic timing and mercurial tenderness under Henry's guile. But Lumley is merely superficial: not a fabulous stage actress. The younger cast members struggle to be three-dimensional and – on a grandiose Gothic set – the medieval costumes (of sparkly, visibly modern fabric) look naff.

Though he ran the RSC for years, Nunn's quality-control faculty seems unreliable these days. His year as the Haymarket's resident director, rather than going from strength to strength, has proved hit and miss.

In Howard Davies's staging of Juno and the Paycock – Sean O'Casey's classic, set in a Dublin tenement in 1922 – the political troubles are simmering outside and the windows are riddled with bullet holes. Yet the stalwart matriarch, Sinead Cusack's Juno Boyle, inset, is busy just keeping her household ticking over; cooking meals; nagging her layabout husband, Jack; or having sing-alongs with the neighbours.

In this joint production between the National Theatre and the Abbey (Ireland's national theatre), the Boyles' home is a Georgian mansion turned into a slum: a few sticks of furniture and shanty-style bedrooms, cobbled together in a vaulty drawing room of grime-grey stucco (design by Bob Crowley).

Juno dances for joy when she learns the family has been left a fortune by Jack's cousin. There's some lovely naturalistic detailing – including the smell of frying sausages – and lots of humour from Ciaran Hinds as the self-aggrandising, booze-sodden Jack who puffs himself up with airs to match his hire-purchase chaise longue. His spindle-shanked drinking companion, Risteard Cooper's Joxer, is both ragged clown and vicious turncoat.

O'Casey's play is cleverly loaded, for this domestic microcosm is gradually revealed to be far from apolitical. It is, in fact, a metaphor for his motherland and Irish dreams. The Boyles' hopes are shattered, the civil war comes bursting through the front door in the form of republican reprisals, and there are radical expressions of lost religious faith, and a startling vein of feminism. The seeds of other plays can be glimpsed here too, from A Raisin in the Sun to Waiting for Godot to Mike Leigh's Ecstasy.

Nevertheless, this isn't Davies at his best. Setting aside the technical hitch on press night when the door jammed – leaving Hinds crying "Has anyone got a key?" and Cusack giving it a good kicking – this production makes O'Casey seem creaky. The cast milk comic moments cloyingly, then sound sententious when tragedy strikes.

At the Almeida, the UK premiere of Reasons to be Pretty sees US writer Neil LaBute back on outstanding form. Steph (Siân Brooke) and boyfriend Greg (Tom Burke) are having a blazing row. She's screaming blue murder as he lies on the bed, protesting his innocence. She has heard that he and his more lascivious mate, Kent, discussed some pretty girl at work, and Greg said Steph's looks were, by comparison, "just regular", but so what.

For Steph, that's a slap in the face, undermining her whole sense of sexual attractiveness. They bust up, cross paths occasionally, try to move on. He's left quietly reeling and having to endure – on his warehouse shifts – the lecherous confidences of Kent (Kieran Bew). Is he then going to say nothing when Kent's wife, Carly (Billie Piper), suspecting adultery, tearfully begs Greg for the truth? (It was Carly, by the way, who informed Steph of Greg's "just regular" comment).

Michael Attenborough's production is terrifically taut, lights snapping up on multiple settings concealed in a revolving freight container. The cast is excellent: no weak links. Brooke is surely up for a Best Actress award, treading a fine line here between social comedy and the scarily psychotic, then touching vulnerability. Maybe Greg (a semi-autobiographical character?) is slightly romanticised as the good guy (patient, loving, strong, witty and well read). However, Burke has his edgy moments. And the play becomes subtly mature, in the end, about the sexes, beauty, carpe diem and regrets, "reasonable" behaviour and moral stands. See this.

'The Lion in Winter' (0845 481 1870) to 28 Jan; 'Juno and the Paycock' (020-7452 3000) to 26 Feb; 'Reasons to be Pretty' (020-7359 4404) to 14 Jan

Next Week:

Kate Bassett reports back on the Tricycle's investigative, verbatim docudrama, The Riots

Theatre Choice

The RSC's exuberant family musical Matilda – adapted from Roald Dahl, with Tim Minchin songs – is at London's Cambridge Theatre (0844 412 4652, booking to 12 Feb). Mark Rylance is glorious as maverick gypsy Johnny "Rooster" Byron in Jez Butterworth's darkening comedy Jerusalem at the Apollo, Shaftesbury Avenue, (0844 412 4658 to 12 Jan).