PRINCE Charles praised the virtues of "free energy" as he officially opened the Stanway Watermill yesterday.

The Prince turned the wheel to produce the first bag of flour made at the mill, near Winchcombe, since the 1950s.

Later he unveiled a plaque to mark the official launch of the mill after seven years of careful work.

Charles paid tribute to engineer Charles Wallis, who began the revival work in 2002 but never lived to see the waterwheel working its magic again.

He said: "When I heard he had died so tragically and unexpectedly it was one of the great sadnesses that has happened. Now we have something which will always live on in his memory."

Receiving a box of flour as a memento of his visit, Charles said: "Free energy, gifted by God, can still be useful in today's world."

Earlier, he met miller Matt Bowman, 45, who had come from the Isle of Wight to offer his expertise.

Mr Bowman revealed Charles had joked that the apparatus "sounded like flushing a large lavatory".

Records of the mill at Stanway House date back to 1291 and by the 18th century, it was a flourishing flour and paper mill.

Around 1850 the cast iron waterwheel was installed and the mill was used to saw timber grown on the estate.

When the village of Church Stanway was electrified in 1913, the waterwheel was the principal power source. It fell into disuse in the 1950s.

Work began to restore the watermill in 2002, and was supervised by Mr Wallis, until his sudden death in 2006.

The finished mill, dedicated to Mr Wallis' memory will open to the public in June next year.