One of four outlying sarsen stones, placed in a rectangle around the inner edge of the earthwork enclosure. Only two survive today.
The stones were named by Edward Duke, a 19th-century antiquary and owner of Lake House in the nearby Woodford valley, who referred to these stones as 'astronomical stations'. The short sides of the rectangle formed by the stones were aligned on the solstices, like the stone circle, and the long sides are orientated to the most southerly possible rising position of the moon. These four stones may have been erected before the stone circle.
