It is very easy to overlook the perhaps unexpected and unwanted consequences of property legislation when getting on with the business of education.  For example you might let another party with whom you are building a relationship or even carrying out research into occupation of a couple of rooms in your building.  If they have a key to those rooms and/or make any sort of monetary contribution, you might find that they have the right to stay.  Although you might be able to prove a ground under the legislation to get the occupier out, it is far simpler and far cheaper to follow the simple exclusion procedure in the first place.  Just be careful who you let into any part of your building and think of your exit strategy before even letting them in.