I've wondered a several of times at how many of the hill forts I've visited might have been reworked Causewayed Enclosures or henges.

Buzbury Rings in Dorset definately feels different to other hill forts in the area and could have been an adapted Causewayed Enclosure. Also Figsbury Ring near salisbury had an inner ditch with a berm.

Plus the seemingly complete lack of causewayed enclosures in the avon valley but the surplus of hill forts (Maes knoll can see 6 or 7 other fortifications) suggests to me at least one of them is on top of a CE.