The photos are of a certain era; in comparison today where one could walk into a studio, create music or noise consisting of musical notes without ever using a single instrument..?
The hobby is known as urban exploration, there is an unofficial code of conduct which is summarised as "take only photographs, leave only footprints", any explorer worth their salt wouldn't take anything or damage anything.
Looking at the gear in general, it's all of a period which suggests it was possibly a band that had some success or maybe even signed a deal and that was their retreat as was the fashion back in the late 60s and early 70s. The WEM PA head and Italian echo, of which a mate of mine has one, were not cheap. It looks like the sort of place someone such as Caravan or The Strawbs, used to have to write stuff together.