Circle of DaysKen Follet, Quercus, £10.99FOR years Ken Follet has been a master of both contemporary and historical fiction. His latest novel, Circle of Days, is an attempt at what is best be described as “prehistoric fiction.”Circle of Days is set in the neolithic Britain, a time after the development of agriculture but before writing reached these shores. The building of Stonehenge is a major aspect of the novel; a monument still standing just a few miles outside Salisbury in Wiltshire, the area referred to as The Great Plain.