Driving north from Bagshot to Bracknell today on the A322 dual carriageway, I received, as before, various alerts to "safety camera" vans. I'm noticing that the

signs in the Thames Valley area are getting bigger, and although there was no van in the layby which is clearly the location that would have been used, there was a post upon which was mounted a very large

sign.
No problem there, but just below the sign I could see a box about 13cm square with what appeared to be a rectangular lens bearing aperture on the front of it. Much of the traffic around me seemed to be going rather faster than 70, though quite safely, so the drivers did not seem fazed by this thing.
My first thought was that it could have been a new type of speed camera, but as a regular reader of this board, I would expect to be amongst the first to know of any new types of camera or methods of deployment, such as hiding cameras in horse boxes, for example.
So I'm wondering if this thing I saw really is a new weapon of mass distraction, or whether it's a dummy to con people into thinking that their speed is being monitored, just as dummy road markings are sometimes used to achieve the same effect.