Carbon dating stone
Dr Andrew Fitzpatrick, of Wessex Archaeology, said: "This is a great result - a very important one.
"The date of Stonehenge had been blowing in the wind. It helps us to be secure about the chronology of events.
"Therefore, in a sense, Stonehenge becomes 'the A & E' of southern England." Modern techniques But without a reliable carbon date for the construction of Stonehenge, it has been difficult to establish this, or any other, theory.
Until now, the consensus view for the date of the first stone circle was anywhere between 2600BC and 2400BC.
Mineral analysis indicates that the original circle of bluestones was transported to the plain from a site 240km (150 miles) away, in the Preseli hills, South Wales.
This extraordinary feat suggests the stones were thought to harbour great powers.
Analyses of his corpse and artefacts from his grave indicate he was a wealthy and powerful man, with knowledge of metal working, who had travelled to Salisbury from Alpine Europe, for reasons unknown.
Strictly speaking, the result was rounded down to "between 2400BC and 2200BC" - but 2300BC is taken as the average.
An even more precise date will be produced in the coming months.
Archaeologists have pinpointed the construction of Stonehenge to 2300BC - a key step to discovering how and why the mysterious edifice was built.
The radiocarbon date is said to be the most accurate yet and means the ring's original bluestones were put up 300 years later than previously thought.