Focus on UK Metal Detecting: Licence to what?

According to their nicely-designed website:

Clinton Devon Estates is a 21st century rural estate and property business. Responsible stewardship and sustainable development are at the heart of everything we do.

So, they will be explaining then why they are issuing "licences" for erosive and non-sustainable collection-driven exploitation of the fragile and finite archaeological resource on their land at Seaton Down. I am sure they will also gladly point us to the records of responsible reporting mitigating the erosion resulting from previous searches of the same land under these "licences". The PAS search engine appears not to be able to demonstrate this.