M an cannot live by bread alone, the saying goes, but bags of flour have given Max Marsden his income for the past 18 years. Marsden believes he may be the only person in the country whose day job is selling professional baker's flour to the public.

A former chartered accountant, Marsden started off with half-a-dozen different flours after a friend in the trade asked him to open a shop in Sheffield. He became so enthused with his new life he bought out his friend and now sells up to 40 types of flour from four outlets of The Flour Bin, all within striking distance of his Derbyshire home.

"People couldn't believe I was just selling flour; and they still can't," he says. Logistics make mail order a non-starter but regular customers from all over the country drive up to stock up, or send a carrier. He even sends supplies in diplomatic bags to the British Embassy in Peking.

What's so special about Marsden's stock is that much of it comes from Canada where cold winters and hot, dry summers make for strong, pest-free wheat and flavoursome bread. Unfortunately for the British home baker, import restrictions and an EC levy make Canadian flour too scarce and expensive for the supermarkets to stock, so most of us don't know what we are missing.

To make tasty, crusty, high-rise bread with body you need a high-protein wheat. Professional bakers are supplied with flour containing up to 14.5 per cent protein whereas we amateurs have to make do with so-called "strong bread flour" from the supermarket with protein levels as low as 9.9 per cent. No wonder we are so often disappointed at the results, even when we have followed a recipe faithfully.

"Canadian flours are so strong they can take anything," Marsden explained. "Tomatoes, onions, olives: you can put what you want into the dough and it will support it." He issues free computer print-outs of bread recipes but clearly likes it best when customers come in to ask his advice or share their bread-making - and other - experiences. Some of his customers still bake on a daily basis; while I was in his shop an elderly woman came in for 0.5kg of flour and 1/2 oz of yeast.

Marsden's flours, packed in sturdy brown bags, are not expensive: 1.5kg of strong white, his best-seller, costs pounds 1.05, or pounds 17.25 for a 32kg sack (kept in a cool, dry place, flour can last for up to a year). Another top-seller at the same price is a Canadian wheat which is about 90 per cent wholemeal but behaves like a white.

He scorns the floppy "easy-pour" flours that have had much of their guts removed but thinks heavy wholemeal bread is a fad. He is also a great fan of bread machines: "the last thing I want to do when I go home is knead dough. Machines, especially the Panasonic, are easy to use and make loaves that rise well."

Other flours he sells include organic, cobber (a malted brown with wheat chips in it), French flour (much weaker than Canadian and used for making brioche), pastry flour (a yellow wheat-maize blend originally devised for Marks & Spencer) and a range of specialist flours such as soya, potato, rye, rice, chapatti and buckwheat, and he is planning to introduce a new durum and wheat flour mix for making pasta.

Marsden would love to have a place in London but the rents are prohibitive and there's a limit on how much you can charge for a bag of flour, however high the quality. Meanwhile the kneady not-so-few are happy to travel up the M1 in order to put beautiful bread on the table.

The Flour Bin is at 36 Exchange Street, Sheffield (0114 2724842). Closed Thurs. Also at Sheffield's Moorfoot Market, Chesterfield Market Hall and Mansfield Market.