The Gold Rush, Filching Manor, Wannock, Sussex<br/> Elsie Piddock Skips In Her Sleep, Salehurst School Playing Field, Robertsbridge, East Sussex

'I can take any empty space and call it a bare stage," wrote Peter Brook 30 years ago, kick-starting a new era of theatre that didn't require a building to give it credence. Today we're no longer surprised to find entertainments out of doors, but expectations tend to be low. So when the Sussex-based The Rude Mechanical Theatre Company pitches up in the South Downs and reels out an absorbing, layered, beautifully scripted and physically anything but crude two-and-a-half hours of commedia dell'arte with The Gold Rush, it comes as a pleasing reprove.

As writer-director Pete Talbot has proved in touring a different show each summer to hayfields, village greens, gardens and cricket pitches across the southern counties, commedia doesn't have to be obscure, or difficult, or set in 18th-century Italy. The background to the current show is the Klondike gold rush of 1897 on the border of Alaska and Canada (the gold rush of the Chaplin film), and its eclectic dramatis personae include Irish and Italian immigrants, Native American prospectors, a sleaze-ridden mayor and his gun-crazed henchman, a lascivious hellfire preacher and a simpleton.

The company wears its historical credentials lightly. Unless primed, you might only dimly register commedia's distinctive physical disciplines at work, or the characters' correspondence to the archetypes of Pierrot, Harlequin and co. But it's depth of study that gives this piece flavour and coherence, and makes it consistently captivating even when we spectators' backsides have grown numb from sitting on grass.

Given a set that's no more than a painted booth, the players must draw the gaze using only their bodies. Often this involves movements to suggest phenomena such as howling wind, a log fire, or the terrors of the so-called Golden Staircase - the mountain pass that claimed the lives of 70,000 poor and desperate hopefuls. Yet the profound anti-naturalism in the show is never arch. Every cast-member, as well as taking several parts, generates sound effects and incidental music, and it soon seems perfectly natural to see characters take up accordion or violin.

There are some classic vaudeville gags - a man tugging a recalcitrant mule, a pair folding sheets to the dimensions of an envelope, the hut-door joke from Chaplin's film - but for all their schooled precision, these moments are almost thrown away. The joy in this production is as much in its script as its physicality - ambitious, since it has to fight wind and weather. Yet in that cleft of the Downs every word rang clear, from Rosie Armstrong's lyrical Oirish musings on love and mortality, to Grant Stimpson's salty expletives, to the mangled threats of Rowan Talbot's Chicago thug: "Kill him, boss? I can't. He's a symbolic stranger." Repeatedly, the players persuade us to believe in their imaginary world and then prick it with a pin. Halfway up a mountain in a blizzard, one character turns to another and asks accusingly: "Are you wearing makeup?"

Modern comedies are routinely described as dark. The Gold Rush shows that today's taste for laughter tempered by grim reality has its roots in commedia, or, strictly, tragedia, its parallel form. Fosca (Death) is the sole stock character who appears here undisguised, lurking halfway up the Golden Staircase to claim his victims. There is no happy ending, yet the triumph of this vibrant production is the lingering conviction that love, friendship, the stream of life and the human spirit all give Fosca a run for his money.

Bags of charm but rather less skill are on display in Paddock Production's theatre-in-the-green touring show Elsie Piddock Skips in Her Sleep. True, this one's for children, but that's surely no excuse for failing to drag spectators' interest from their crisp packets. I blame the mothers, who set such an appalling example to their fidgety offspring that the poor blighters don't even stand a chance of listening to the end of the term "attention span". There is also, in this otherwise rather lovely story from Eleanor Farjeon, the handicap of an adult male fairy character called Andy Spandy. There's earthy magic, though, in Martina Clarke's titular Elsie Piddock, a girl so good at skipping that she wins the lifetime sponsorship of the local sprites, and at the age of 109 defeats a dastardly land-developer by skipping him into a hole in the ground. The odd thing is that throughout the professional performance, nobody actually skips, they only pretend. Yet in the audience-participation stint, several impromptu turns - one a lady with silver hair - manage double-ropers, hops, and backwards skipping too.

jenny.gilbert@independent.co.uk

'Gold Rush' tours till September ( www.therudemechanicaltheatre.com).

'Elsie Piddock' tours till next weekend ( www.paddockproductions.org.uk).