AN expert from Bournemouth University has helped to pinpoint that Stonehenge was constructed in 2300 BC and its bluestones were erected 300 years later than previously thought.

The monument could have been a place of pilgrimage for the sick and injured of the Neolithic world, equivalent to an ancient accident and emergency in Southern England.

Professor Tim Darvill of Bournemouth University and Professor Geoffrey Wainwright, President of the Society of Antiquaries of London, believe the henge's bluestones were revered as healing stones.

Burials near the site were of people cured of injuries and disease, amongst them the Amesbury Archer.

Originally more than 80 bluestones were transported some 250km from the Preseli Hills in west Wales to Wiltshire and placed at Stonehenge. Today, fewer than one third remain.

From late March to mid-April, the two professors led a group of experts as part of the Bluestone Project to determine when the first Double Bluestone Circle that formed the original Stonehenge was placed on the Wessex Downs.

Their two-week excavation within Stonehenge from late March to mid-April this year - the first allowed since 1964 - yielded a variety of prehistoric materials including pottery and worked flint.

The trench excavated had proportionally more fragments of bluestone than sarsen stone and most of the pieces had been deliberately broken off the standing stones.

Fragments of charcoal from the excavation dating to 7330 to 7070 BC shows that things were happening at the site much earlier than previously thought, but what that entails remains a challenge for future work.

New radiocarbon dates also allow the construction of the Double Bluestone Circle to be tentatively dated to the period 2400 to 2200 BC, a few centuries later than originally thought.

In generations spanning 2300 BC there was the death of the Amesbury Archer and his companion, the shooting of the young man buried with fragments of bluestone in the ditch at Stonehenge, and the construction of The Avenue linking Stonehenge with the small watercourse in Stonehenge Bottom.

During that time, a large stone was also erected in the entrance to Stonehenge.

Professor Darvill said they had been able to re-write whole sections of Stonehenge's history from the small excavations they had undertaken.

"All of this evidence reinforces the idea that whatever the purpose of Stonehenge might have been - and there could well be more than one - the bluestones were central to it.

"Their meaning and importance to prehistoric people was sufficiently powerful to warrant the investment of time, effort, and resources to move the bluestones from the Preseli Hills to the Wessex Downs."

Funding of the excavation at Stonehenge, an English Heritage site, and post-excavation analysis, was provided by BBC Timewatch in association with the Smithsonian Network in the USA.

Dave Batchelor, Stonehenge curator at English Heritage, said: "We are looking forward to seeing the results of the full analysis, but from what we understand so far, we believe they have added valuable information to the chronology of Stonehenge."

A documentary about the work entitled Stonehenge Deciphered will air on BBC 2 on Saturday at 8pm.