This was never called 'Mount Caburn' until outsiders named it so. Its name is 'The Caburn.'
Any site members should see the late 1990's archaeological report: they found out some remarkable things, and put to bed the idea of The Caburn as a hill-fort, through hi-tech as well as inspired techniques.
Amongst these was 'the shout test'. They placed volunteers at intervals round the (round-topped) hill. They shouted as if to warn of attack. Nobody could hear anything from the others. It would never have worked as a defensive position (except perhaps in WWII when there were AC-AC nests there). They DID find over 139 holes, not post holes, deliberately dug, sometimes as pits with shelves and ritually-placed objects in them. The ancient entrance/exit is placed in the ritually important north-east.
The ditches do seem to have served a defensive purpose but only very much later than its original ritual purpose, and very temporarily.