isnt it a hill fort or some other type of ground works?
in looking this up (post answer), im pleased to report though there are a good 15+ Sussex words for mud. (bostal isnt one)
thought Thunder Bolt did the best in post 4, the "of England" means essentially the same thing, though literally speaking i dont believe the Romans saw any difference been England and Scotland as a place (just the tribes here were inside or outside the tent). trouble with words is often have...