Late to the party, only just learnt of this, authors Lock and Ralston. The book form comes at a price now, and the online version is currently inaccessible as it is being upgraded. Anyone used it?
If we're referring to the same thing... I had a look and thought, 'that's handy'. However, I recently read Toby Driver's "Hillforts of Iron Age wales' and he mentions it in there. I love a good hillfort, me.