Also bear in mind that in relation to what you're saying about the area being the first ridge above the plain, back in the mesolithic, it's reckoned that what's now the coastline used to be the first ridge visible from the coast. Hence things like the mesolithic house at Howick. But, it also means there a quite a few BA burial sites dotted along the present coast. Cists occasionally pop out of the dunes after storms, like around Low Hauxley. Just to mention just a few off the top of my head, there's a cist at Beadnell, supposedly right on the edge of the dune line(it's on keys to the past), as are the now lost bits of rock art from Seahouses, North Sunderland and Bellshill quarry. The iffy cups of Alnmouth, the cup marks at Wandlylaw, the possible rems of a stone circle at Early Knowe.Then there's whatever may be hiding under the foliage of the Kyloe Hills. Could be allsorts of stuff kicking about. I think the main prob is that over the centuries, the coastal plain has been so heavily worked, that people thesedays assume that any prehistoric stuff will have long been used for building anti-reiver defences, or enclosure walls etc. Each time I go past Hulne Park, I wince to think how much rock art may have gone into the many miles of the Duke's backgarden wall.
It's good to see that someone's going out and looking :)