Stonea Camp is an Iron Age hill fort near March, not far from me in Peterborough. The book, Stonea and the Roman Fens was brought to my attention by Phil on the TFL list, knowing my interest in the Fens as they were around the time of the Dux Britanniarum setting. It's written by Tim Malim, the archaeologist responsible for a lot of excavation and restoration of the Stonea site in the early 90s.
In a nutshell? Fascinating. If you want a feel for what the Fens looked like around the time of the Romans (answer: wet) and a much deeper look into the archaeology of the area than you'd ever get from (say) Time Team or one of the more sweeping books on the English landscape, this one's for you. I'm still working my way through it, because there's just so much to delve into.