Thank you, Anne.
Waves and Time isn't so far away, but it's modern, and not the place to which I've referred. And I'm told that Pastscape is far from 100% reliable, so I was not discouraged when unable to find these earthworks listed there. So far I'm happy to rely on the reference I remember seeing recently which calls these earthworks "Bronze Age" although it might have been in a walkers' guide, or similar website only.
Something is not right. This message is just to keep things from messing up down the road