The Marlborough Pudding

It has been common knowledge that the pudding shaped mound in the grounds of Marlborough College was probably a smaller version of Silbury Hill. It is now official – see www.guardian.co.uk/science/2011/may/31/malborough-mound-wiltshire-silbur… and www.pasthorizons.com/index.php/archives/05/2011/marlborough-mound-a-sibl… and was built in mid third millennium BC. A thousand years ago it became the base of a Norman castle and somewhat later, in the 17th century, was garden landscaped as an oddity. The evidence comes from a coring probe in which charcoal from the centre of the mound was C14 dated to 2400BC. Now, all that is required is an explanation of why it was built – and at that point in time?