Unlikely Information
Hi, Just caught this question on a search, a bit more info.
My Father was Project Manager for the testing of the engines. I remember spending a few weekends with him driving around to look at suitable railway tunnels. I didn't remember where it was but your post identified it.
Once the test-bed was set up dead birds were collected to be fired in to the engine. As stated it was to prove a disk destruction would be contained within the housing: it was.
There were problems with some break-ins, the company put up various hazard signs to scare away local youths (presumed responsible), it worked but then they had to take them down a reassure the local council there were no such hazards.
My Father was also responsible for the flying test bed, placing an Olympus in the bomb bay of a Vulcan bomber.
Hope this helps.