OK - so it's not so much of a What the...? anymore because in the Part 1 post here Pete guessed it pretty quickly - so they are officially bases for a Harrier hide or dispersal site.
So I finally got a little more work done on them this weekend. The bases have been base coated and given a quick dry-brush - so they now look like this:
Now they need to be grassed and then the metal "decking" added in the 3 lines on each base.
I've also started work on the camouflaged netting shelters. Here 3 of them not long after being made - still very wet with glue & water:
Finally - here's a couple of photos of my prototype shelter I made the day before - all dry and ready for the next stage - placed on top of one of the bases so you can better imagine how it might eventually look.
Not perfect by a long shot - but pretty reasonable and I'm happy with them so far.
That's it for now - need to take a couple more photos and then the next post will be a tutorial on my US Woodland Cam.