"Me thinks we had better get back to the Silbury problem as the demo is almost upon us."

True. And although these speculations about similarities with other mounds are interesting, I don't think we should let them divert from the reality that Silbury is a totally unique superstar in terms of sheer size and construction, or from the fact that it's without predecessors, parallels or successors!

But then, I'm a bit biassed!