It is important to be precise about what the Government's new planning framework threatens. It does not (generally) threaten special areas, such as National Parks or Green Belt land. What it threatens is the ordinary, open countryside of green fields, hedges and woods which gives England in particular its character. In the past, ordinary countryside was explicitly recognised as of value in planning policy guidance for its "intrinsic character and beauty" and given robust protection for that.
The Government proposes to do away with this protection entirely. Add to this the scrapping of the principle of building on brownfield land first, and the new presumption in favour of development and you have what amounts to the biggest relaxation of countryside protection since the modern planning system was introduced more than 60 years ago. This was spotted instantly by the National Trust and the CPRE.