I find any private airport interesting, and this one is particularly so, primarily because the two hangars appear to be entirely underground.
I did some detective work to see what company or individual would have A) the resources and B) the need for a location enviable by even the most discerning Bond villain, and discovered that there may be a link with Land's End, headquartered in nearby Dodgeville.
The structure on the far left of the second photo would support this, as it appears to be some kind of large theater or presentation hall.
Further investigation suggests that the property may have transferred ownership to the owner of a building/construction company.
Whomever the owner may be, he or she is certainly fortunate to have such a magnificent lair. I can only imagine how amazing it would be to wake up, shower, shave, get dressed, and then stroll through a tunnel to your airplane, safe and sound in its underground hangar.