Another curious point, there is a small 'barrow' immediately outside the eastern entrance to the fort at ivinghoe, and it always surprised me when i visited that it was seemingly undamaged (apart from what looks like later interference at the top).
Despite the respect afforded, you would think the general area of an entrance to a hilltop fort to be at times a very busy place and a place of considerable work. The barrow lies almost directly in front of the entrance.
Ive read it may be a 'midden', maybe reinterpreted for that very reason, but does that seem likely? Are middens usually found in such locations, outside a fort entrance in particular?

edit - poss cursus was from geophysical survey in 2000 rather than aerial photography