With the arrival of spring comes the first crop circles of the year, in the shadow of the 19th-century white horse carving at Milk Hill near Alton Barnes.

Formed in the bright yellow oil-seed rape, the crop formations are a familiar sight for Wiltshire residents.

But the crop pattern phenomenon has sparked heated debates around the world over how exactly they are formed.

Some believe they are created from a microwave effect, in which the field is bombarded with hundreds of thousands of volts of electricity from the ionosphere. This softens and bends the hollow oil seed rape stems.

Crop pattern hunter and expert Lucy Pringle photographed another pattern at Avebury, close to Silbury Hill.

She also took pictures of another pattern near Stonehenge. She said: "This is the first batch of crop patterns this year, and I think they're lovely."

Ms Pringle has been involved in long-running research into the effects of electromagnetic fields on living systems in crop circles and boasts the UK's most comprehensive crop circle photographic library.