The discovery of this second avenue of sarsen (large grey stones) solves a neolithic puzzle that has confounded historians and archaeologists for nearly three centuries. Until a mechanical digger struck the top of the first stone to be revealed amid the chalk and clay soil of a farmer's field last week, the only known pre- historic stone avenue in the area was that leading to nearby West Kennet.
The discovery of the parallel pairs of megaliths, linking the Beckhampton long barrow, just south-west of Avebury, with the henge itself, settles a controversy that has excited academics since the beginning of the 18th century.
A Lincolnshire antiquarian, William Stukeley, said in the 1720s that a second line of stones might exist. He argued that what he dubbed "the Beckhampton Avenue" had a pivotal role in the ceremonial activities and spiritual beliefs of the people who erected and visited the ancient monuments in and around the village of Avebury.
His theory was based on years of field observation and the examination of classical and historical texts. In 1743, he published his conclusions in Abury: a Temple of the British Druids. (Abury was then the village's name.) Stukeley's ideas were dismissed by many at the time and since as mere guesswork, lacking any firm basis. A 15-strong team from Southampton, Leicester and Newport, Wales, universities drew a blank last year when they excavated the same field to test Stukeley's notions about Avebury's "missing link".
Joshua Pollard, a co-director of the excavation, said that their discovery this summer "forces us to rethink the whole nature of the Avebury complex".