Although Swamp Juice is a shadow puppet play of countless props, brilliant effects and elemental danger, it’s actually put together with all the low-tech ingenuity and low-budget sparseness of a crude home movie, or the sort of parlour game your clever uncle would devise before we all took refuge in computer games.

You enter the theatre to find the Canadian puppeteer Jeff Achtem grunting and scratching himself on a stage full of odd bits and pieces. The scene is like a jumble sale hit by a hurricane. There’s a washing line of stuff, a free-standing easel, a few lights and a white screen.

Out of this, and a clever soundtrack, Achtem devises a black and white animated cartoon featuring a pair of snails, a snake, a bird with a cockatoo hairstyle and a Bart Simpson-ish goofy hunter, all of whom set off in a canoe along a river and are swallowed by a crocodile.

The stroke of genius is that Achtem remains at the centre of the action – “Achtem, achtung” – so that we see him struggling to manipulate his limbs and fingers into position while juggling the cartoon characters, sometimes dropping things and getting his own knickers in a right old twist.

The story accelerates, and Achtem hands out reeds, fronds, wobbly rubbery things and mop-like sea anemones to the audience. When lit from behind by a single torch, these create a living, heaving sea-bed.

Three large screens are deployed in what now becomes a 3-D adventure movie — the glasses have been distributed – and we’re assailed by flying jellyfish and a cascade of bubbles as the bird whizzes round our heads (“Eat your heart out, Avatar!”) pursued by the hunter in an old-fashioned bi-plane.

It’s Blue Peter magic on a shoestring, a crude theatrical budget bean-feast to delight children of all ages; and it sends us home to start pulling out our toy theatres and cardboard boxes, candles and torches, all over again. The very root of all theatre has been celebrated.