For a start, I knew that the entire Harwell site used to be RAF Harwell, a bomber field during WW2. Then ...
This monument is right at the edge of the site, next to the A4185 shortly before it joins the A34. On the other side is this plaque:
Just in case your graphics aren't up to it, it reads:
"This stone marks the end of the runway from which aircraft of No. 38 Group, Royal Air Force, took off on the night of 5th June 1944 with troops of the 6th Airborne Division who were the first British soldiers to land in Normandy in the main assault for the liberation of Europe."(A quick note: I've also been to where the 6th Airborne Division was heading - Pegasus Bridge, in Normandy, the first bit of Europe to be liberated. So I've been to both ends of the flight.)
Turn 180 degrees from the monument and you see this:
The end of the historic runway in question - now just wasteland. You can just make out the curve of the Diamond Light Source doughnut halfway down. Note also the crane sticking up at a 45 degree angle, for reasons I will come to.
In the picture below you can just make out the runways of RAF Harwell, courtesy of Google Maps (picture obviously taken a couple of years ago, hence Diamond being a big circular patch of mud).
Letters (a) and (b) show the two ends of what was presumably the main runway, now Fermi Avenue. (c) and (d) are the two ends of the historic runway; the monument is at (d). And this is why it has attracted my interest because here is a close-up of (c), the start of the historic runway:
... right at the end of our carpark. I've been parking yards away from a bit of history for the last 2.5 years and I had no idea. The crane mentioned above is being used to construct the building shown here. That's how we treat our heritage.