Never heard of it? You will. And you are probably old enough to remember it. It's those cheap and cheerful Staffordshire crocks with spindly motifs that passed for modern art in the Fifties and Sixties. Do not mock. Lord Queensberry and Sir Hugh Casson designed some of them, as did Terence Conran when fresh out of art college.
A 1955 six-setting Nature Study dinner service by Conran, with wiry dragonflies and leaves, was snapped up at the opening for pounds 1,200. When I told Sir Terence, he thought for a bit, then said: "In my opinion that's considerably more than it's worth."
But who dares to doubt the eye of the dealer-publisher who co-discovered the Victorian silver designer Christopher Dresser and held a sensational sell-out exhibition of his wares back in 1972, who hoarded grotesque turn- of-the-century Martinware birds that can now sell at auction for over pounds 40,000, and who sold his pioneering collection of corkscrews for pounds 107,000 at Christie's South Kensington last year?
It takes Mr Dennis, 60, up to 10 years to quietly amass a saleable stock of some unsung collectable - lately, mostly pottery - whose time, he judges, is about to come. While building his stock, he will have bumped into a knowledgeable collector capable of writing a definitive guide book cataloguing for the first time Poole pottery or Royal Doulton stoneware, children's china or Whitefriars glass.
Then suddenly the champagne corks pop, hitherto unconsidered trifles jump out of junk shops and into collectors' display cabinets and prices at auction surge. The scrums at Mr Dennis's openings are all the more intense because collector-investors are given the chance to snap up the pieces photographed in the guide book. Unbeatable provenance.
Richard Midwinter, son of Roy Midwinter, who controlled the crockery company from the late Fifties until his death in 1990, remarked at this week's opening: "My father wasn't interested in people buying to collect. He just wanted them to live with a design for two or three years then pass on to the next."
His mother, Eve, added: "I used to warn our designers, `Don't get too precious - this is the kind of crockery that husbands throw across the kitchen if dinner's late'."
But Magnus, Mr Dennis's 24-year-old son, had a different tale. He remembered since the age of 10 playing under the whitewashed arches of his family's cellar, near his father's publishing house in a disused village church in Somerset, trying to avoid toppling the lovingly hoarded stacks of Riviera and Cannes tableware designed for Midwinter by Sir Hugh Casson in 1954 and 1960. Single dinner plates by Casson start at pounds 40 and one with a rare shape sold at the opening for pounds 300.
What next for the Dennis treatment? I can whisper that in September it will be Denbigh ware, "the most successful British ceramic company of the Nineties - technically wizard", complete with up-to-date guide.
Then, you would never guess, jigsaw puzzles. Especially wooden ones from between 1900 and 1950. Mr Dennis has "a few hundred stashed away". Raid your grandmother's cupboards immediately.
After Christmas: crockery bearing designs by the whimsical Fifties and Sixties French cartoonist Peynet - the little scarecrow-like lovers with pageboy haircuts, he with a bowler, she with a bouquet. "They're amusing," says Mr Dennis. "They say something to me." Moreover, the Japanese are fanatical about Peynet - they have devoted a museum and erected a statue to him in Tokyo. Mr Dennis has collected 200 different Peynet designs and models in a decade.
The origin of his unerring eye? His early days in the Fifties, running a bric-a-brac stall in Bermondsey market: "When people have only pennies to spend, you soon find out what they like. " He spent 1966 touring Mexico and South America, snapping up mid-19th century French glass paperweights for pounds 20 that later fetched pounds 100 at Sotheby's. He had swept floors at Sotheby's, ending his six years there running its glass department.
It was to Bermondsey market that he returned after opening his gallery in 1967, this time as a buyer, noticing that nobody seemed to be buying Royal Doulton stoneware and that virtually nothing had been published about it. Four years later, after buying about 500 pieces of it, he held a selling exhibition coinciding with the publication of the first two of his series of eight books on Doulton.
A 1913 Doulton crinoline lady that sold for a fiver in the late Sixties is probably now worth pounds 150-pounds 200, a rarer one costing pounds 20 then could fetch pounds 2,000 now. "It seems to be a rule that after 20 or 30 years rarity adds a second nought," says Mr Dennis.
"Always buy the best. Only by collecting can you really find out what's rare, what's common and what stands out. And publishing a book about a subject has nearly always meant that the market for it has improved. We give patterns and dates. Collectors like to relate to a book - it gives them confidence."
But the book must tell a good story: such as the story of the first studio pottery in Britain, founded by the Martin family. Their quirky but beautifully modelled salt-glaze stoneware birds, sold in Holborn, caricatured politicians and judges and were an in-joke.
"The family history reads like a Victorian novel. They earned only enough to subsist. They fired only two or three times a year and sometimes lost the lot. One brother went mad because the shop burned down and the sister died after being bitten by a monkey."
The exhibition is open until 7 August. "Midwinter Pottery" by Steven Jenkins, pounds 18 from bookshops or post-free with free publications catalogue from Richard Dennis Gallery, 144 Kensington Church Street, London W8 4BN (0171-727 2061, fax 0171-221 1283) or Richard Dennis Publications, The Old Chapel, Shepton Beauchamp, near Ilminster, Somerset TA19 0LE (01460- 240044, fax 01460-242009).