Yes, Prime Minister, Festival Theatre, Chichester<br/>Ditch, Old Vic Tunnels, London<br/>Peter Pan, Barbican Theatre, London

A staging of 'Yes, Prime Minister' updates Margaret Thatcher's favourite sitcom &ndash; complete with hung parliament, misbehaving foreign politicians and an unhealthy dose of cynicism

The British PM has only just taken office but, with a pesky hung parliament, he's facing a Cabinet revolt already. Indeed, it's all going farcically wrong for David Haig's Jim Hacker in Yes, Prime Minister.

This post-election comedy by Antony Jay and Jonathan Lynn brings the Westminster characters from their much-loved TV sitcom up to date.

That's to say, this time round, Haig's Prime Minister Hacker – floundering just as amusingly as Paul Eddington ever did in the part – is striving to play the Churchillian statesman while foisting Britain's debts on to his successors' shoulders. He is signing up to a loan-for-oil deal with Kumranistan – geographical co-ordinates hazy, moral compass mislaid.

Hacker is luxuriously ensconced in his mansion, Chequers. His close advisers are also in attendance, including, of course, his top civil servant Sir Humphrey Appleton. Henry Goodman is smooth and wily in Nigel Hawthorne's role. Nonetheless, all hell is about to break lose as their overnight guest, the Kumranistani finance minister, wants more than a nightcap.

Hacker is horrified when Sir Humphrey's sidekick, Jonathan Slinger's nerdy Bernard, announces that the foreign VIP is demanding an under-age call girl. Outrage rapidly gives way to ethical equivocating and preposterous spin about how it is far, far better for one teenager to get screwed than the whole European economy.

I have to say I found this more depressingly cynical than hilarious. At the same time, I admired the flash of Swiftian, satirically sharp teeth. There is an undermining weakness, though, in the plethora of sub plots – taking in sulking Americans, U-turns on global warming, the BBC Director General and illegal immigrants. Lynn and Jay struggle to work all these into the escalating farce, and be up to the minute. No hung parliament Deputy PM gets a foot in the door.

The main new character is Claire (Emily Joyce), a swanky special policy adviser who vies with Sir Humphrey but whose character isn't yet quite in focus. Goodman's darting fits of panic are more droll, as is Haig's comic timing, chest puffed with bravura then deflating like a popped balloon.

In Beth Steel's new play Ditch, it becomes clear that whoever has gone on to win the next general election hasn't saved the planet. We've been catapulted into the future and have landed in a near-apocalyptic Peak District. This off-site Old Vic co-production is staged in a huge dank cavern under Waterloo station: a dark maze of brick arches. Set designer Takis has created installations to establish the grim mood. A dead hare hangs above a pool of blood. Sinister metal cages, apparently made from bedsprings, stretch into the distance.

Watching Richard Twyman's strongly cast production – performed on a circle of mud – you glean that Derbyshire is now a militarised zone. Danny Webb's whisky-swilling Burns is (just about) maintaining control of a small unit of jackbooted soldiers, on the look out for "illegals". They are also being dispatched to fight over an oil pipeline, an international conflict that could turn nuclear. Meanwhile, the lads are surviving on deer, snails and the odd potato grown by the camp cook, Dearbhla Molloy's Mrs Peel – a terrifically tough old bird.

The political situation remains frustratingly murky and Steel's scenes need more dramatic momentum, yet this writer has a fine ear for dialogue and warm humour, and the cast is terrific. For all its doom and gloom, Ditch shows great promise, transferring from Halesworth's fast-rising festival of new writing, HighTide.

Wendy Darling's fantasy realm, Neverland, isn't quite as much fun as expected – either for her or the audience – in the National Theatre of Scotland's touring production of Peter Pan. David Greig's new adaptation of J M Barrie's classic has notable strengths. For starters, he makes Wendy's father a Scottish engineer overseeing the construction of the Forth rail bridge. So its vast girders span the stage like pirate rigging (design by Laura Hopkins), and a gang of rivet boys dangle from it, flirting with danger and our pubescent heroine (Kirsty Mackay).

That night she dreams of flying, in her bloomers and bodice, with Kevin Guthrie's muscular little Peter Pan, a cross between a bare-chested satyr and an untouchable urchin, so damaged by an unloving mother that he is emotionally stunted. At points, Cal MacAninch's tattooed, kilted Captain Hook looks like Peter's increasingly dark side too, his full-blown demon.

Barrie's psychological subtext – including suicidal tendencies – is clearly understood though never crudely spelled out. That means John Tiffany's production is still suitable for children. Yet its magical moments are too few and far between. Tinkerbell is bewitching: a whisking flame with no visible strings attached. By comparison, Peter's aerial feats aren't awfully big adventures, mainly just bobbing around on a giant rubber band.

'Yes, Prime Minister' (01243 781312) to 5 Jun; 'Ditch' (0844 871 7628) to 26 Jun; 'Peter Pan' (nationaltheatrescotland .com) touring to 19 Jun

Next Week:

Kate Bassett samples Paradise Found, the Menier's new musical