Local historian Brian Edwards found an eyewitness account of the Drax 1776/7 dig which mentions there was wood from top to bottom in the center of Silbury.
This was most likely planks to shore up the sides to stop the delicate layering falling in not a bloody gurt pole sticking out of the top.
If there was a pole then it would not be very effective as the landscape around silbury is not flat, which would be necessary for a shadow casting gnomen.
Is the article you mention on line RG?
Back to Bert bashing ;-)
Pete G