Not only privately owned but a listed property by Historic Scotland and such drastic excavations as might be required to expose the suits of armour or other artifacts would have to pass muster in that bailiwick as well. Like so many things in this world, it does work like Mickey Rooney shouting with an irrepressible grin "Hey, let's put on a show!" or in this context "Hey let's dig up some suits of armour" And if you think its unusual, try digging for artifacts around Stonehenge, or Notre Dame de Paris or at the site of the Battle of the Little Bighorn. Private ownership is only the beginning of the issue, set rules for archaelogical excavations and undending bureaucratic red-tape are just a couple of others.
Would that it were not so complex but it seems it's a condition of that business called life.
P.S. This is quite some background colour you have willed us!