THEORIES abound about what causes crop circles such as these giant examples near Alresford.

Many say hoaxers, some blame aliens, some the weather, but others blame it on shifts in the Earth's magnetic field.

The last theory is being put forward by researcher Colin Andrews, a former Andover-based electrical engineer.

It is a return to the spotlight for Mr Andrews whose book Circular Evidence was a best-seller in 1989 co-authored with Alresford man Pat Delgado.

The book helped spark the worldwide interest in the phenomenon and, with follow-ups, has sold some 250,000 copies.

Mr Andrews once argued that some form of extra-terrestrial intelligence must be responsible for the circles. Now, after years of research, funded by the Rockefeller Foundation in the USA, he argues most of the circles and particularly the complex ones are hoaxes.

That means disappointment for UFO-watchers who have been excited by the recent arrival of these two just south of the A31 Alresford bypass near Bishop's Sutton. Mr Andrews believes they are almost certainly man-made.

But the genuine circles are the result of crops being electrocuted into the distinctive circular patterns, he says.

He was due to speak today at a three-day convention which started yesterday in Andover. Organised by the Centre for Crop Circle Studies, it features 20 speakers from across the world. Mr Delgado, of Arle Close, Alresford, told the Daily Echo yesterday: "In Circular Evidence in 1989, I mentioned magnetic theory. It is a possibility. But this type of mystery can stand up and slap you in the face.

"It is a mystery within a mystery within a mystery. There is something there that is inexplicable. It would be arrogant of us to say we know the answer."

Mr Delgado said of the enduring interest: "People love to feel involved in a mystery. This is their way of being involved."

He said many hoaxers now used computers to generate their images. He said he had inspected the two circles at Bishop's Sutton and labelled them hoaxes.

Among those not welcoming the two circles is the farmer. A polite notice at the field gate says, optimistically: "Please keep out."

Converted for the new archive on 25 January 2001. Some images and formatting may have been lost in the conversion.