The Norman Conquests, Old Vic, LondonNo Man’s Land, Duke of York’s, London Love’s Labour’s Lost Courtyard, Stratford-Upon-Avon

Stephen Mangan’s Norman clasps his latest conquest in his arms. Ecstatically sozzled, he has his tongue down his brother-in-law’s throat. Yes, it’s all gone skew-whiff – this family reunion in the country – in Alan Ayckbourn’s cryingly funny trilogy, The Norman Conquests.

Tearing himself away, Paul Ritter’s gobsmacked Reg flops to one side as his neurotically bossy wife, Amanda Root’s Sarah, freezes on the patio with her eyes on stalks. As for Mangan, he is running wild or, rather, hobbling wild, tanked up on dandelion wine, his trousers round his ankles.

A stroke of genius by artistic director Kevin Spacey, the Old Vic’s revival of this 1970s hit is triply wonderful. First, it’s a buzz-inducing big event, with the full triptych on Saturdays. Second, the theatre itself has been delightfully transformed. The stage is now in-the-round, with the audience seated in a snug 360-degree loop. Third, and vitally, Matthew Warchus’s cast are all superb – playing three tense siblings and their infuriating partners.

Ayckbourn is famous for structural game-playing and here the weekend’s adulterous shenanigans are run and rerun from different vantage points: the dining-room in “Table Manners”, the lounge in “Living Together”, and the lawn in “Round and Round the Garden”. A certain jigsaw-puzzle satisfaction is to be had, even if the middle play feels a little like filling.

What’s far more interesting is the deepening moral unease inspired by Mangan’s Norman, for this maritally unhappy Don Juan is charismatic and irresistibly droll. He appears to have fallen truly in love with Jessica Hynes’ frazzled singleton, Annie. But the more seduction scenes you see, the more uncertain you become. Is his romantic tenderness just an act, and how much tragic damage will he eventually cause?

What also knocks you for six is the unexpected poignancy amid the laughs. This is Ayckbourn’s English-backwater answer to Chekhov: a portrait of disappointed lives and simmering frustration. Ritter’s transition from hilarious motor-mouthed nerd to silent weeping is unforgettable.

Knocking back the booze is an excuse for more damped-down clowning in Rupert Goold’s revival of Pinter’s No Man’s Land, whose premiere came within a year of the Ayckbourn trilogy. Michael Gambon’s wealthy recluse, Hirst, makes a sloshed beeline for his glittering drinks cabinet. With his pale, bloated face and glazed stare, he forms a bizarre double act with his incongruous guest, David Bradley’s ragged Spooner. Hovering like a scraggy crow, he scavenges on the sly while pontificating like a wannabe philosopher-poet.

The comedy is wisely restrained, for Hirst’s Hampstead Heath mansion is a lugubrious realm, an alcoholic’s limbo. Gambon’s Hirst is a carcass of a man, half-dead already, and Bradley might be some ghoulish visitant – Death disguised as a tramp. Goold brings this out subtly, without imposing any radical directorial concept.

The disappointment comes with the celebrity casting of David Walliams (of Little Britain). This is, clearly, his bid to move into serious stage drama, playing Hirst’s peculiarly possessive houseboy/heavy, Foster. Though not without brooding menace and a trace of camp, his is a rather stolid performance, perhaps nervously inhibited, but without much comic or other flair.

In Shakespeare’s Love’s Labour’s Lost, David Tennant’s Berowne has sworn to live as a bookish recluse with the would-be academic King of Navarre and other courtly buddies. This is sheer folly. Scarcely have they abjured the fair sex than the Princess of France and her teasing, pretty retinue intrude.

Tennant is a highly amusing livewire in Gregory Doran’s Elizabethan-dressed production, his native Scots accent and cheeky youthfulness bringing a vibrant swagger to Berowne’s sardonic quips. Unfortunately, that doesn’t stop this early romcom looking sketchily underdeveloped. Tennant’s Berowne and Nina Sosanya’s bright, spiky Rosaline barely have time to fall for each other. The supporting cast, meanwhile, have their exuberant moments, especially Joe Dixon’s dandified Don Armado – fanning his codpiece. In general, though, everyone struggles with this work’s endlessly ornate rhetoric, often just lists of synonyms. Words, words, words.

‘The Norman Conquests’ (0870 060 6628) to 20 Dec; ‘No Man’s Land’ (0870 060 6623) to 3 Jan; ‘Love’s Labour’s Lost’ (0844 800 1110) to 15 Nov