Good to see your rational overview of the Silbury/Egyptian connection Steve, and I cant argue with anything you say. Just to play devil's advocate for a moment though. Silbury is a five-stepped 'pyramid' (same as the Saquarra pyramids). Why did the Silbury builders opt for five steps? Silbury sits close to the River Kennet. The etymology of 'Kennet' is interesting but, in a nutshell, it stems from the word Cunt. Interesting, because the fertile region of the Nile is known as the Kehmet.
What I really find interesting in modern arguments about the Silbury/Egyptian connection is the sort of 'reverse argument' that it just cant be. Not so, I've discussed this elsewhere but, again in a nutshell, I'm convinced there was far more travel between Britain and the ancient 'classical' world than we give credit for. I've never been to Rome for example. Alfred the Great, however, more than a thousand years ago went there several times :-)