The latest pages of Pagan Britain are focusing on some of the more modern notions of British NeoPaganism. There's more "such and such an idea is disproved by the record" arguments here, which is a little confusing, because for much of the book there hasn't been proof one way or the other. I believe there are no "lack of proof is proof of lack" errors going on -- Hutton is cautious, and, once again, the interesting details are in the end notes.
The latest chapter is addressing an underground paganism in Britain during the Middle Ages. Hutton here is addressing the theories of James Frazer and Margaret Murray, which supposed that Christianity was a thin veneer over a native Paganism, and which took its cue from Geology and Evolutionary Biology in terms of "primitive cultures" developing into (European Colonial) "enlightened cultures." Other than commenting that modern historians pretty much agree that no underground Pagans existed despite the notion lingering in the popular imagination, he hasn't come out and said that in so many words; rather, he's focusing on the evidence.
Margaret Murray theorized that Sheela na gigs carved on stone walls of cathedrals and castles were evidence of medieval pagan worship carried over from ancient prehistory. Hutton says that it is "almost certain" that Murray's theory inspired Lady Raglan's similar theory concerning foliate heads (a.k.a., the Green Man). According to Hutton, it seems more likely the Sheela na gigs are not representatives of an underground goddess, but protective vulvas carved on to castles to safeguard them. The foliate heads were not hidden worship of an underground Green Man, and probably started out life in Christian churches as carvings on baptismal fonts as something baptism protected against. (More over here: http://johnburridge.blogspot.com/2011/05/review-hidden-spirituality-of-men.html )
Hutton pause to mention that while the ancient Pagans apparently didn't secretly worship the Goddess and God as Sheela na gig and foliate head, they have become energizing elements of modern NeoPaganism.
From stone carvings, he moves to sacred trees and sacred wells. Hutton points out that worshiping sacred trees or at holy wells is a common human action, and then points out that there's very little evidence that Christian places of worship were built on top of old pagan ones. Various sacred trees (yew, apple) in early Christian Britain seem to have come along with Christianity from the Mediterranean. (I'm a little surprised Hutton didn't bring up Robert Graves' calendar of trees, although that might be a straw man argument by now). Also, medieval churchmen wrote about their frustrations over the superstitious practices surrounding holy Christian wells (oh, and candles, but that's from another book). There's a focus on Bath, which at first seems to be an outlier. Hutton points out Bath was abandoned, and so saw no continuous worship, and that there was a Christian fashion to honor the dead with depositions of goods in water.
The more I think about it, the more candles (which may come up later) are a kind of example of what Hutton's trying to get at in this chapter. Ancient Pagans may have used candles at some point in pre-history. Medieaval and modern Christians certainly do. But finding evidence of candle use in churches from 1000 AD does not mean that there were secret Pagan rites going on in churches back then (although there are accounts of churchmen being vexed with parishioners collecting Christian candle stubs as talismans and good-luck charms).
... and the last fifty or so pages await.