The engine running or detuning pens were originally built to test the aircraft engines for the Hunter.
Three pens were arranged in a curve. One has been completely removed.
Of the two remaining; the unique example survives that was used to test all ‘jump jets’ or VTOL. The VTOL pen is lined with metal sheeting and sound absorption. Channels below ground take extract for the jets nozzles. Historical significance is for the development of the ‘jump jet’, P1127 through to the Harrier. All aircraft engines were tested and run here before being assembled and shipped worldwide.
The two engine running pens were given Grade II Listed Building status in December 2017. Historic England’s detailed Listing report