It has but don't know how to find it . An excavation might help clarify .There seems little doubt about the pits and their width but not what they contained , timber posts are possible but as we don't know the depth of the pits we can't guess at a possible height of the posts . Roger Mercer suggested something like a ratio of 1:3 iirc for a max height . If they were pits for timbers then it would seem a waste of energy to have metre wide timbers cut down to a couple of metres or less .The depth of the ditch is unknown and I don't believe there is any way of knowing the height of the bank if there was one .

One has to wonder if people would go to all that trouble to construct nine concentric rings of such huge timbers to form an arena for just gaming in. I would have thought it was for a far more important reason than that. We keep going back to the religeous aspect of these sites and if that really is the case then to put this astounding amount of effort in with the most basic of tools would put its reason far above anything we believe in today IMOO.

i'm always drawn to the central areas of these mass posted circles because I think that may be where the answer lies. What was there that needed so much protection?

Now to go off on a tangent for a moment. I train sheepdogs for herding and sheepdog trialling and for part of this use what I call a round pen for starting dogs off in. It's 75ft in diameter with a single 6ft wide gate. Now a keen working dog (or killer stray dog) will do anything to get to its sheep including jumping barbed wire sheep netting if it can find no other way of getting to them. A hungry or wild dog will turn heaven and earth to get a feed so you need high class security fence-wise to keep them out.

With Stanton Drew in mind I removed the gate to my round pen and secured two 6ft wide sheep hurdles to the gate posts extending out into my surrounding field. So viewed from above I had a circle with two 6ft hurdles projecting from it and a dozen sheep in the pen.

Across the original entrance line I stuck fencing stakes 12 inches apart into the ground. 12 inches out from that I stuck in more stakes but staggered them to cover the 'gaps' created by the first line.

Obviously you had no trouble seeing directly through this setup but after going inside the pen I called my dog to me who I'd left on the outside. He came through to me after just a short hesitation.

However I then filled out that 6ft deep entry into the round pen with dozens of our fencing stakes (the plastic ones with a spike on the end) all randomly stuck in the ground but still 12 inches apart. Still easy for a dog to get through one would think, but that's as far as it got, because he could not work out that he had to wind his way though them to reach his goal. Yes of course I could have trained him to do that because he was a Border Collie but he would never have done it of his own doing because he would have been fearful of getting stuck in there and not getting out. In the wild any sign of fear shown by a wild dog and it would have been attacked by another as it has exposed its weakness.

So I wonder if that was the reason that the central area of these circles was protected so well, to stop predators gaining entry. The mass and width of those timber posts would not have allowed anyone, let alone wild animals to see through to the cental area or even consider entering even if they ever did firstly cross the formidable ditch.

Can you imagine the spec for this job and the foreman getting his men together on the first day.
'Right lads, first things first. Sharpen up your stone axes were going off to cut down 500? trees and all with a diameter of 3ft'...any questions?'

'Okay, okay...who just shouted out 'get stuffed?'