Thanks for Info, Knocker.
Had a look, as you mentioned, they have set up a frame above a grassy area which will be a prominent feature on the junction of the new road that will be built right next to it.
They have also fenced off the grassed area North of Harriet engine house, blocking off several paths with no signage! (ie you walk 20 yards up the track and find it fenced off).
Is it safe to come out of the bunker yet?