The information was collected over a period of 65 years by Frank Gregory who died in 1998, aged 81.

His collection of more than 100,000 documents was bequeathed to the Weald and Downland Open Air Museum, near Chichester.

Very little of his lifetime's work has been published until now and, in addition to providing a unique insight into the changing rural landscape in Sussex throughout much of the last century, his detailed records of mill construction are seen as a valuable technical resource for people wishing to restore mills throughout the country.

Acknowledged as an unrivalled authority on the subject, both nationally and internationally, Frank Gregory's interest in wind and watermills stemmed from childhood walks with his family around the Downs near Brighton.

He became fascinated by the construction and operation of the many mills he encountered and took to photographing and sketching them. He began visiting further afield by bicycle and then at weekends by car.

During this period, the 1930s, many of the mills were still operational and Gregory kept records of the construction and condition of each mill visited. Becoming a woodwork teacher only helped to increase his knowledge of construction and mechanical matters.

Windmills at Nutley, Polegate, Shipley, West Blatchington and Oldland all owe their preservation to his expertise.

The current project, which is being lead by the Mills Archive Trust and supported by the Sussex Mills Group, will see volunteers working to index, catalogue and digitise Gregory's records and illustrations, all of which will be made available online.

The project will not only bring the history of the Sussex mills to a much wider audience of local residents and museum visitors, it is expected to generate more interest in volunteering to help restore and care for the surviving mills in the area.

For the Mills Archive Trust, chairman Dr Ron Cookson said: "We are very privileged to have access to Frank's collection. He created a vital heritage asset and we will be able to give the world a glimpse of the man's influence and importance."

Commenting for the Heritage Lottery Fund, Sheena Vick, South East England Regional Manager, said: "This work will ensure that Frank Gregory's unique collection of material is protected and conserved for future generations while providing a valuable resource of technical data for those concerned with restoring important aspects of the county's rural past."

The project continues until 2010 when it will conclude with a national symposium in London.

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