The entrance to the Butterfly House in Godalming, Surrey  If a caterpillar awoke one morning from uneasy dreams to find it had metamorphosed into a detached house in leafiest Surrey, it might look like this. The Butterfly House is a mutation of a 1930s timber-framed design once shown at the Ideal Home Exhibition. With its bright winged canopies, serpentine pathways and garden that twists through its science-fiction interiors, it must surely be one of the most surreal homes ever to have been built.  Intriguingly, this is not the brainchild of some Mad Hatter-turned-architect but a design by Laurie Chetwood, an architect best known for business parks, branches of Sainsbury's, redesigns of Underground and bus stations, hotels, offices and a distinctly sober-looking brewery.  The Butterfly House is Chetwood's plaything: a building, part mechanical, part organic, that has been growing, as if by itself, from a high bank overlooking a bowl outside Godalming in Surrey for the past four years. It is at once an artwork, a laboratory for architectural experimentation, a part-time family home, a design studio and an attraction, planted with lavender, hebe and buddleia, for bright clouds of butterflies. Constructed of timber, Kevlar sails, steel, copper and plastic ducts, two kilometres of bungee rope, over 100 metres of fibre-optic cables and 50 interwoven carbon-fibre fishing rods, it comes as a delightful shock.  The house is inseparable from its garden, a tangle of natural and artificial roots, tubers and plants. It is hard to tell, as you walk up the ramp to the front door, where nature ends and architecture begins. As the light falls, this extraordinary entrance begins to glow. The light is from the tips of hundreds of fibre-optic cables, as if a swarm of fireflies had come to replace the diurnal butterflies.  Only when you walk into the raised glass entrance lobby do you realise that the house is indeed a gigantic artificial caterpillar in the process of transforming itself into an equally artificial butterfly. The winding entrance path is the multi-legged, pulsing caterpillar; the entrance lobby contains the chrysalis, wrapped around and mutating above a brightly coloured stairwell; the Kevlar sails that burst from the garden in front of the house and flap gently in the wind are the wings of the butterfly. This gigantic insect has wrapped the old house and its studio wing in its tendril-like embrace.  As for living rooms, kitchen, principal bedroom, these are like nothing you have experienced before. Chairs hang from ceilings, tables with folding wings are raised and lowered into position by pulleys, beds sway in webs of rope. Pipes and wires coil and recoil through the kitchen and the bathrooms like jungle creepers in childhood dreams.  The Butterfly House is unprecedented, yet its sometimes dreamy, sometimes nightmarish interiors owe something to the imaginations of Lewis Carroll, Franz Kafka and Jules Verne. There are references to pop art designers such as Roger Dean, and to films by, among others, Terry Gilliam, or Jean-Pierre Jeunet and Marc Caro. The former's Brazil comes to mind, and the latter's The City of Lost Children.  Chetwood's head is full of this sort of stuff, and he is probably the better architect for it. His practice produces intelligent buildings that push boundaries gently: the elegant, "eco-friendly" branch of Sainsbury's near the Millennium Dome in Greenwich; a hotel in Clerkenwell that will sip rather than guzzle energy. He experiments before he designs, so clients get the benefit of the latent mad scientist and thoughtful artist in him without having to pay for buildings that are expressions of his creative frustrations writ large. Too many new buildings seem like the work of architects wanting to play the role of bad boy and brat girl artist. If they kept their games within the confines of computer screens, sheets of paper and cardboard models, we would all benefit. Chetwood plays games with the house, but not with us, his clients or the streets we live and work in.  Yet the Butterfly House is ultimately more than a vision of an architect let loose on high days and holidays. The house really is a research laboratory. It allows the architects of Chetwood Associates to experiment with new materials and technologies. It enables them to explore new forms, to rethink the house and its relationship to both nature and technology. It asks questions about our relationship with new electronics and gadgetry.  Given its experimental nature, the house would be an unsettling place in which to live for long spells. Because it is an R&D lab, it relies on a secret old kitchen and service room that are pressed into use on days when it is used as a family home. The architect, his wife and young children live in a flat in north London; they go down to the Butterfly House to test its latest wiles, gizmos, protrusions and unexpected growths.  There is much to do here. Some of the electronics are troublesome: a car radio on a revolving Perspex stack of shelves is powered by a car battery; sliding seats wobbling around a suspended dining table feel as certain as riding a camel must do for the uninitiated. But none of this cannot be put right, or replaced. Chetwood will keep playing until the garden is bright with butterflies.  Many of our best designers and engineers are tinkerers and tamperers by nature; the more they experiment and test new materials, forms and technologies, the better for the rest of us - most of whom have no wish to buy, use or live in experiments. This has happened far too often over the past 50 years, when people, often those with little or no choice, have been used as guinea pigs to test new forms of housing design and technology. The Butterfly House, far from being a fictional nightmare, proves to be a fascinating and, if sometimes delirious, happy dream.
How do you get into the Butterfly House? Easy - just walk up the caterpillar and through the chrysalis in the lobby, says  Jonathan Glancey.