For all their peaceful image, watermills are places of constant sound: creaking timbers, rushing water, the whoosh of corn from the hoppers and the persistent grind of the great millstones.

For George Eliot, these sounds brought a “dreamy deafness” as she stood outside Dorlcote, the “Mill on the Floss”. In the many mills that have now been restored for both historical interest and practical use, the visitor can experience the same sense of heightened peacefulness.

More than 500 watermills were mentioned in the Doomsday Book, most of them devoted to grinding corn into flour. Today’s mills are usually on ancient sites but include very little, if anything, of original buildings.

At Letheringsett in North Norfolk, for instance, the present mill was built in 1802, although the mill site had been moved a couple of hundred yards downstream early in the 18th century. This had the practical effect of increasing the head of water and therefore the mill’s power.

On the other side of the country, the mill at Otterton in East Devon has remained on the same stretch of the river Otter for over a thousand years, despite periodic declines in demand and the gradual silting up of the river.

Harnessing the power of water required the creation of a mill stream or leat and the careful operation of sluice gates to control the flow on to the wheel.

Water power drove the early stages of the industrial revolution but from early times had been used for more than corn milling. At Otterton in the 15th century, for example, there were two fulling mills where cloth was beaten to give it body, and a water-driven forge.

Also in East Devon, the Coldharbour Mill at Uffculme used water power to drive wool-spinning machines until the middle of the l9th century, when steam power took over.

The real romance of the water-mill, though, is in the grinding of corn to flour. Arriving in sacks, the grain is winched to the top of the building and then gravity-fed into the hopper. From there it travels into a shallow wooden trough called a shoe and passes through the eye of the top stone - the runner - and is ground between that and the bed stone. To ensure the grain keeps flowing, there is a jiggling mechanism known as a damsel or damozel.

While the bed stone remains still, the runner rotates. Each stone has a pattern chiselled into the face and the corn is ground as the cutting edges on the two stones pass each other. The flour spills from the sides of the stones and collects in the wooden tun which surrounds them. It then passes down a chute to the floor below.

Millstones must never be allowed to run “dry”: the face can be damaged or sparks start a fire in the dusty atmosphere. For that reason the miller must control the flow of flour, usually by a string attached to the shoe or to the hopper.

The popular idea of the jolly miller who “worked and sang from morn till night; No lark more blithe than he” comes from the otherwise little-known 18th-century poet Isaac Bickerstaffe. Today’s millers are people devoted to the idea of restoration as well as flour-making.

Michael and Marion Thurlow had no previous milling experience when they first leased Letheringsett in 1987. Since then they have rebuilt the mill’s wooden floors, roofed the building and realigned the water wheel.

At Otterton 10 years earlier, Desna Greenhow had found a mill in similar state of disrepair. Main beams over the wheel chamber had rotted and a pair of millstones sagged through the first floor. Although she was able to open the mill to the public later that year, restoration work continued over a long period.

Now, as well as producing quality flour, the mill is visited by thousands of people each year, houses professional exhibitions in the first-floor gallery, and has a number of craft workshops in the courtyard behind.

For school parties, the attraction of visiting a working watermill is the combination of historic and aesthetic curriculum possibilities. The sights and sounds of a mill can stimulate creative ideas while the fact that it has operated in essentially the same way for hundred of years provides a real insight into the past. Outside, the roar and splash of water as it powers the great wheel contrasts vividly with the peacefulness of the millpond.

Children may also appreciate the difference in quality between stone-ground flour and the rollered product, which, by the second half of the 19th century, had already started the decline of the small miller. Although many struggled on against the odds, it took a combination of the wholefood movement, environmental awareness and historical tourism to revive this previously common riverside feature.

* For further details contact: Otterton Mill, Otterton, East Devon. Tel: 0395-568521; or Letheringsett Watermill, Letheringsett, Holt, Norfolk NR25 7YD. Tel: 0263 713153.