Britain is a nation of inveterate inventors. At its core is a select band that keeps on innovating despite repeated rejection, writes Roger Dobson
Bob Richards takes a pole with two wheels attached to one end from his car boot and swiftly attaches it to a waiting supermarket trolley. As he pushes the laden trolley with its extra wheels around the Tesco store, he demonstrates how easy it is to turn corners at the ends of aisles without needing the upper body strength of Frank Bruno to persuade the castors to change direction.

"You can turn right when you want to, not when it wants to," says the retired RAF engineer as he glides smoothly and effortlessly past fresh fruit and veg and into jams and preserves with only a hint of a swerve of the hips. But despite its success in trial runs at Tesco in Wolverton in Buckinghamshire, the Trolley Tamer has failed to attract the interest of the big companies that might develop the idea.

"No commercial interest so far, I'm afraid, but we are working on it," says Bob. "Some shops seem to feel it gives the impression that their trolleys don't work properly."

Bob, who experimented with his own test trolley to perfect the patented gadget, is a one of Britain's band of inventors, a burgeoning group of modern-day shed-dwellers who let nothing stand in their way of finding solutions to questions that have never been solved - or, in some cases, neverasked. These are the men - for there are few women - who laugh in the face of technological adversity and pour scorn on the suggestions that at the hi-tech end of the 20th century there is little left for the home-alone inventor.

Some, such as Paul Bone, the creator of the double-decker cat tray, the Sellotape-cutting thimble and the Tooth Fairy's Magic Kingdom game, have given up almost everything to pursue the development of their invention. Some make money from their inventions, and over the years a small elite, such as the inventors of the drink-can ring-pull, the Workmate, cat's- eyes, and Tupperware, have made really serious money.

David Wardell, editor of Inventors World, says Britain is still a world leader in turning out inventors. Too often, he says, they are portrayed as balding, absent-minded chaps tinkering with foaming test-tubes or getting electric shocks off Heath Robinson-type gadgets, and shouting "Eureka" every time something works. "There is a historical perception of inventors as nutcases in sheds rather than having great value to the nation."

But he adds: "The Japanese Ministry of Trade did a survey and calculated that 50 per cent of all the commercially viable inventions in the world since the end of the Second World War have come from the UK, 25 per cent from the United States and 5 per cent, Japan. We are still pre-eminent when it comes to inventing, but hopeless when it comes to commercialisation."

Business at the Patent Office at Companies House in Newport, Gwent, reveals how busy the inventors have been. In the past 12 months, there were 26,000 applications for patents, of which nearly 10,000 went through to the final examination stage. About 5 per cent of these probably come from individuals rather than companies.

According to the Institute of Patentees and Inventors - membership 1,000- plus - around 3,500 patents each year are granted to Britons. Some inventors, such as Paul Bone of the Isle of Wight, are prolific. Mr Bone has patented 16 inventions - small beer compared with the 1,093 amassed by Thomas Edison, but considerable by modern standards.

"I started thinking it was the same as any other business, but it is not," he says. "I sold my house to follow this trail and two years ago sold the last piece of antique furniture we had.

"I have been concentrating on a controllable watering can with a button operating a valve, but I couldn't get a single watering can company interested. I eventually started doing it myself and sold about 1,000 units in the first year. It has great potential - if 5 million gardeners used this can five times a day for 30 days, they would save 2.25 billion gallons of water."

Bill Courtney, a former physics teacher, is also a prolific inventor with four patents to his name and 12 applications in the pipeline. He has spent pounds 15,000 on patents and prototypes, but with little return. Gadgets such as the expanding dog lead in the shape of the double helix of canine DNA and an optical rear-car spoiler that allows the driver to see blind spots are among the inventions that have failed to find commercial support.

"I do a lot of inventing while I am out hill-walking, or in my study," Mr Courtney says. "All the answers are extremely negative. Only one in three manufacturers bothers to write back, and when they do it is always the same type of standard letter. It is frustrating, but I accept they have to be conservative. If we were too bold, we would have killed ourselves off long ago."

A lot of small-time inventing still goes on in sheds, garages, attics and cellars, largely because these are the kinds of solitary habitats favoured by inventors as places where they can dream and scheme alone. Studies show that, for the most part, their inventions are not earth- shattering or revolutionary. It is the little riddles in life that occupy their minds: why don't shopping trolleys steer in a straight line, how do people with no arms raise toilet seats, why do socks get lost in the washing machine?

Some gadgets are developments on a theme, such as the discreet dog muck remover, which is cunningly disguised as a walking stick for the pet owner who would rather not get too close to the stuff. Offending muck is grabbed by jaws secreted at the base of the walking stick and quickly stuffed inside. At the next bin, the owner can casually dump the stick's contents.

Other inventions are quite unexpected. Take, for example, the self-disinfecting toilet seat (yet to find a big-time backer), which contains a reservoir of disinfectant that is released through a system of tubes and tiny holes when the seat is raised.

Andrea Gordon stands to make a million from her sock-saver - a tiny foot-shaped piece of plastic with two star-shaped holes, designed to keep pairs of socks together in the wash. No such fortune yet, alas, for the inventor of the automatic clothes hanger counter for people with large wardrobes. Run the wheel of this device along the wardrobe rail and it will instantly reveal how many hangers there are without having to count them.

Other crackpot inventions seeking patents recently include the foot- operated toilet-seat lifter, the any temperature snow-making equipment, the ultimate back stretcher, collapsible golf clubs, the breathing observational bubble or underwater motorbike, a plastic device for carrying more than one carrier bag at a time, and a ski-conversion kit for bicycle wheels.

Such bizarre inventions are not a new phenomenon, says Paul Ambridge, secretary of the Institute of Patentees and Inventors. He recalls the headache and general malaise-eliminating machine of 1927 which involved a potentially dangerous mixture of a bathful of water, a metal skull cap for the occupant to wear, and electricity. It was not, by all accounts, a success.