Jill Mill, Clayton, West Sussex. The Jack and Jill Windmill Society will be receiving a plaque from SPAB in recognition of their work. © Mildred Cookson

The engineers of yesteryear obviously knew nothing of the concept of inbuilt obsolescence. Some of their finest work, in the form of mills, is still in action today, doing the jobs they were designed to do two or three hundred years ago. In addition, they all conform to today's standards of sustainability, being run on air and water.

In celebration of these excellent machines, from grain-grinding windmills to water-powered textile works, National Mills Weekend 2008 will see more than 300 historic mills open their doors to the public on May 10 and 11.

The annual festival is organised by the Mills Section of SPAB (the Society for the Protection of Ancient Buildings), and activities that will appeal to all the family will take place, including demonstrations and the chance to buy flour and other produce made on the premises.

Mapledurham Mill, Oxfordshire. © Mildred Cookson

"This event has grown year on year," said Simon Hudson, of SPAB's Mills Section. "We are delighted that so many mills are taking part in 2008. The popularity of National Mills Weekend shows how important these wonderful buildings are, both in terms of our national heritage and our landscape."

"And, with increasing interest in natural food production and sustainable power sources it's hardly surprising that people want to find out more," he added.

Some of the mills that will be open include a Whitchurch Silk Mill in Hampshire, a woollen mill at Trefiw near Conwy in Wales, and the country's largest water-powered cotton mill at Styal in Cheshire.

Maud Foster Windmill, Lincolnshire. © James Waterfield

Many mills are open to the public on a regular basis. An illustrated guide to these, 'Mills Open', is available from SPAB Mills Section.

Many of those open this weekend are run by members of the Traditional Corn Millers Guild, set up in 1987 to promote stone ground, wholemeal, oatmeal and other special flours to a wider public and continue the tradition of milling with stones.

Some of the advantages of flour produced in this way include that it is 'cool-ground' – meaning it has not gone through the chemical changes produced by high temperatures generated in modern roller-milling, and flaky bran gives a wholesome flavour and texture to bread.

Other mills still produce textiles as they did centuries gone by, such as the luxury silk from Whitchurch – but the staff now include no children, fortunately.

The owners of Wicken Windmill in Cambridgeshire with their plaque, during National Mills Weekend 2007. © Simon Hudson

SPAB Mills Section protects hundreds of traditional wind and watermills and campaigns for and advises on the sympathetic repair of mills. It co-ordinates a plaque scheme to give formal recognition to groups and volunteers who care for windmills.

On Saturday May 10, Jack and Jill Windmill Society will be receiving a plaque from SPAB in recognition of their restoration work on the pair of corn mills perched on the South Downs. The plaque will be presented by Jim Woodward-Nutt, Chairman of the SPAB Mills Section at 12 noon.

For full listings of mills taking part in the National Mills Weekend 2008, see the SPAB website.