There are very few details regarding the mast available, but what I did find was that it is a former USAF radio relay station, and is around 200 feet or so tall. The mast is a US Air Force microwave relay station and part of the Digital European Backbone network. This network linked the EUCOM war headquarters at High Wycombe, Bucks to the Upper Heyford F-111 base. In 1990, $210,000 was allocated in the US Defence budget to provide heavy security precautions at the site. The second site in the area - a short distance along the road - was also a microwave relay station used by the Civil Aviation Authority to relay radar to the air traffic control centre at West Drayton.
Out and about with @slayaaaa and on our way to look at something else and we just happened to drive towards this. The weather was good, so we decided it would be a nice little spot to stop for lunch. Once over the fences and in the site we climbed to the top and proceeded to have lunch and watch the world go by…