Think xmas (!???) pudding was the last theory I heard....

Moth

PS Knew I shouldn'ta gone to the Moulin Inn with thos Scottish Megaraks.

PPS Pregnant belly makes sense to me.

Try 'The Avebury Cycle' by Michael Dames for a complete load of tosh!

Most people will describe Silbury as an Omphalos, a navel or central point in the landscape.

Remember that when built Silbury looked nothing like it does today. It was white and stepped and did not resemble a mouldy Xmas pud in any way - perhaps one with lashing of brandy sauce though?