Natural England was previously called English Nature.
Natural England is the Government organisation responsible, amongst other things for designating areas as SSSIs. Site of Special Scientific Interest. This designation gives specific, legally enforcible protection to the site.
The introduction to the citation for Hackfall as an SSSI is as follows:
Hack Fall Wood occupies the steep north and east facing slopes of the Hack Fall Gorge, along the River Ure north-west of Ripon. It is important as a largely undisturbed example of ancient semi-natural broadleaved woodland and it contains a wide range of plant communities.
Status: Site of Special Scientific Interest (SSSI) notified under Section 28 of the Wildlife and Countryside Act, 1981, as amended.
Natural England have set out what their vision is for the management of the site and have a schedule of activities that are either absolutely precluded or which need specific permission before they can be started. This has meant that all plans and proposals by the Hackfall Trust have had to be approved the Natural England before work is started. Any work which is proposed in the future will possibly also require Natural England approval. Whilst this is in many ways positive it may cause difficulties. Natural England’s starting point is the situation that of the wood in 1989 but at that time it was in a very neglected state. Restoration involves, to some extent, taking the wood back to a more managed state that existed prior to 1931. Those involved in planing and managing the restoration have a difficult balancing act to achieve.
You can obtain copies of documents relating to Hack Fall Wood SSSI by following this link and selecting the documents that you require.