On Mrs Chamberlain's stand at the Miniature Heritage Show, there is a goggling array of minuscule objects. She has tiny, gleaming knives and forks, tiny mixing bowls containing two tiny egg yolks shining on a bed of flour, a tiny tureen of peas topped with a tiny knob of melting butter. The stars of her catalogue, however, are the little jellies on thumbnail- sized plates. They're moulded into the traditional hillocky shape, just like the kind you'd find in Noddy's pantry. They have the lustre of real jelly. The yellow variety even comes topped with slices of lemon so minute you'd need surgical tweezers to pick one up. Most important, these jellies wobble. Actually wobble. Squish them and they bounce back. This is Mrs Chamberlain's triumph. For years, miniaturists have been experimenting to find the formula for a mouldable, durable wobbly jelly substitute. Mrs Chamberlain's discovery means that her business, Magnolia Cottage Crafts, now has the edge on the hundreds of others chasing the catering contracts for doll's house kitchens. Naturally, she won't divulge the recipe. "It's a closely guarded secret," she explains. "Nobody else has got it yet."
She's right to remain silent. Small-scale industrial espionage is rife in the doll's house world. There's little that practitioners can do to prevent their designs - for, say, tiny candle-snuffers or bacon rashers - being pirated by other suppliers. After a cheerful old lady called Jennifer has shown me her tiny Turkish carpets, and explained in some detail how she makes them, she fixes me with a serious stare. "If any of that goes into print, there'll be trouble!" It's not kid's stuff, this. It's an adult obsession, and not a cheap one. A good ready-made doll's house can cost over pounds 1,000. Commission an expert to build you one from miniature bricks and mortar, and the price goes up to pounds 30,000.
There are around 450 British businesses serving the doll's house trade. In the past 10 years, the number of miniaturist fairs in the UK has rocketed from eight a year to 650. Though most exhibitors insist that their profits are as tiny as their replica parsnips, this is a booming industry, fuelled by the grey pound. A glossy monthly magazine, Doll's House World, runs ads that mimic estate agents' blurb ("fine aspects front and back ... highly recommended for the first-time buyer"). DHW also reports on the latest innovations: rusting agents to add realism to your miniature boot scraper, variable flicker units to allow your gas light to surge as if some tiny Charles Boyer had tampered with the mechanism; minuscule jars of pickled onions crafted by celebrated specialists. On the magazine's website, devotees pool ideas on the problems of reconstructing the world in 1:12 scale. "Can anyone help me find a way to make realistic-looking water without using resin?" asks enthusiast Linda Lunken. Someone named Oswalda Henriksen has e-mailed a reply: "Clear glue. Making sure it does not make bubbles."
The creation of small things is difficult work, requiring a battery of secret skills. "If you made a miniature oak table out of oak, it would look completely wrong," explains Mr Johnson, a doll's furniture maker with 21 years' experience. "You can't just use the same materials." The Johnsons are masters of detail: their pies have sections of crust cut away, so you can glimpse a virtuoso display of infinitesimal peas and carrots. Their minuscule marrows are hand-streaked with veins of yellow and green. Mr Johnson's dinky stepladder even has rings of paint on the top step, where some careless doll's house painter has plonked his tin of Matisse Blue.
There's a gaping division between those who make their own products from scratch, and (say it with a sneer) "importers" - those who buy in cheap stuff from Taiwan and China. The makers take great pride in their work and in their narrow specialisms. A rather severe lady in Judith Chalmers make-up shows me her collection of tiny lacy bras, which she refers to discreetly as her "haberdashery". Mr and Mrs Collins display their 0.3mm drill-bits that you have to squint to see if they're actually there. Mr and Mrs Mason have driven from Southend-on-Sea to sell their miniature "floosies", buxom odalisques in basques and suspenders which - in the nicest possible way - bear a slight resemblance to Mrs Mason herself.
They know that what they do is a little peculiar. "My husband tells me I'm absolutely insane," guffaws Mrs Chamberlain. "It's probably a disease of some kind." Her fellow exhibitors concur. "Some people said I was slightly mad," admits a Mr Hooper from Devon, recalling how he gave up his day job in order to make miniature ironmongery and brasswork. His knobs and knockers are acknowledged as the best in the business, but he still seems slightly dazed by the silliness of it all. Susan Allen (of Chicken Little Miniatures in Guildford) makes Lloyd loom furniture and her friend Jennifer Morshead (of Moorhen Miniatures in Dorking) makes tiny Victorian shell- sculptures under glass domes. When I ask them what drew them to the business, they dissolve into giggles. "You just have to be completely insane!" they chorus. Then, as if to add weight to her statement, Susan goes on to explain why she wove her first piece of doll's furniture, a miniature cot: "I had this tiny porcelain baby who had nowhere to sleep."
Mr and Mrs Smith, whom I meet admiring Mrs Chamberlain's wobbly jellies, proudly show me a kitchen range they've bought for their Victorian home. Every hinge and grille found on the full-size version is replicated in 1:12 scale. The cost? pounds 180. And an extra pounds 149 if you want a set of fire- irons to go with it. "Some of the people here are absolutely bonkers," says Peter Smith. I gently suggest that he and his wife must be a bit bonkers themselves if they've just paid pounds 180 for a doll's kitchen range. "Absolutely," they return.
Mr Smith, who, rather oddly, turns out to be the general secretary of the Association of Teachers and Lecturers, reveals his taste for small- scale Gothic. "My wife always wants to create these sedate domestic scenes, but I fancy something a bit more dramatic," he confesses. "Something like a maid weeping on the bed and the youngest son of the household slowly putting his head around the bedroom door ... "
Miniaturists love to gossip about the bizarre extremes of other miniaturists, possibly in order to make themselves seem less loopy. One man tells me of a replica of Leeds Castle that sold for pounds 28,000. A doll-maker confides that she often gets orders for amputees, though she can't guess what they're used for. And there are rumours of more macabre, MR James-ish behaviour. One stallholder describes how a customer came to her with an order for six wreaths and six coffins, after a wave of disease - presumably cholera - had struck down the inhabitants of her little Victorian residence. Perhaps more disturbingly, I'm assured that some people replicate their own homes in miniature, and have filled their doll's houses with tiny replicas of their own family.
There are, I suppose, a handful of cod-psychological explanations for why people should become fixated upon such a hobby. Are they withdrawing into a second childhood? Are they control freaks, wanting to recreate a miniature world in which there is perfect order? Are they aspirants, creating magnificent Georgian townhouses inside poky living rooms on Barratt estates? Are they fantasists, escaping from tedium or unhappiness into households that are frozen into tiny tableaux of domestic bliss? The last one is well documented: Vivien Greene - the doll's house collector and widow of the novelist Graham Greene - seems to have used the miniature world as compensation for the misery inflicted upon her by her husband's infidelities. The 1920s film star Colleen Moore is reputed to have made the same retreat into small-scale fantasy. Looking around the fair at Croydon, however, none of the enthusiasts here seem remotely unhappy.
However, there's just one thing they'd like outsiders to get right. Just as William Shatner fans get prickly if you call them Trekkies rather than Trekkers, doll's house collectors do prefer to be referred to as miniaturists. It's an odd word, that. Rather too close, I think, to naturists. Especially as so many of its practitioners are middle-aged couples looking for something to spice up their retirement. And on the evidence of Croydon, miniaturism - like naturism, wife-swapping and morris dancing - is one of those semi- secretive eccentricities of middle-aged suburban life which deserve to be celebrated more widely. People talk rather seriously about skateboard culture and rave culture, but the miniaturists are a genuine subsection of British society, utterly dedicated to a project that is simultaneously admirable and lunatic.
One of the most dedicated is Peter Turvey, a well-known character on the circuit. A striking figure with large square glasses and the copious beard of a Bible-belt survivalist, he is one of the only manufacturers of doll's house building materials in the world. His houses are built exactly as a real house would be, with bricks, mortar, cement, plaster and concrete - all scaled down to 1:12 or 1:10 scale. He isn't yet taking commissions, but when he does, customers will have to stump up somewhere in the region of pounds 30,000 for a six-bedroomed residence. A brick-built doll's house, he says, takes as long to build as a full-sized house. In the meantime, customers are snapping up the materials to try it for themselves.
Turvey has an unusual background for a doll's house maker. Brought up in Zimbabwe, he studied civil engineering, taught maths, set up his own poultry farm, founded a school specialising in mathematics, fought Robert Mugabe's guerrillas in the bush, and suffered a near-fatal bite from a cobra. It took seven years for the effects of the snake toxins to abate. He and his wife, Margaret, and their seven children returned to Britain in 1979, and were moved into a tower block in Brixton. Then, in 1995, the Turveys suddenly decided that their future lay in the doll's house industry. Looking for an unfilled niche in the market, they set about trying to make miniature bricks strong enough to build with. It took nine months of experimentation before they came up with the formula. They designed their own tools to create the correct moulds. They concocted their own ultra-fine mortar mixture - the grains in a substance like mortar also have to be scaled down in order for it to bond miniature bricks. They devised ways of making tiles, window frames, paving stones and lintels.
In the window of Grandad's Toys - the Turveys' shop near Godalming - is their first construction, a summer house supported by brick columns, canopied with an elaborate tiled roof. Mr Turvey removes the top to show me the intricate woodwork hidden beneath. "The tables all face outward so you can look out at the view," he explains, as if forgetting, momentarily, that it's too small for human habitation. The public area of his shop is dominated by scaled-down building sites, and everywhere there are his ingeniously improvised devices: a rack built from MDF and bulldog clips, used in the production of window frames; a home-made press, used to stop the delicate tiles from curling like day-old cucumber sandwiches. The kiln - which can fire 27,000 bricks at a time - sits in the hallway, and in the back workshop, thousands of bricks are stacked upon shelves, like slabs of Lilliputian chocolate. Everything is in perfect order.
Peter Turvey's intense interest in the miniature world offers some clues to its wider appeal. For him, tabletop building projects such as a house, a fully working water mill, or a lych gate offer a freedom of action that he sees as sadly lacking in the upscale world. "Protectionism in this country is rife," he argues. "Building here, I've got no one to tell me what to do. If I want to change the position of a kitchen door, then I can do it. If this was a real house, I'd have to go to a planning committee and consult nine or 10 trade unions. Which is absurd!" And he lifts a little mortar on the back of his improvised steel trowel, and cements another brick into place
Ann Mason's Dolly Clobber (01702 618213); Audrey Johnson Quality Miniatures (014895 78420); Chicken Little Miniatures (01483 35307); Country Mouse Doll's Houses (01233 770526); Grandad's Toys (01483 420957); Moorhen Miniatures (01306 627233); Magnolia Cottage Crafts (01371 873845); Miniature Heritage Shows (01753 890794)