A profile of the mound (comparing it to Silbury) is here along with the position of the 6 cores (4 from the ditch) that were taken. It’ll be interesting to see if analysis of the ditch samples shows that it predates the Norman moat... if so the similarity with Silbury (and perhaps Waden Mound as well) is striking, and the fact that Marlborough Mound is now thought to date from around the same time as Silbury (2400bce) suggests a much wider, perhaps culturally related, backdrop.