There is a recent satellite view on Google Earth (https://www.google.ch/maps/@55.7082578,-3.8019207,2458m/data=!3m1!1e3). I assume the different amounts of growth reflect the various trees which were initially planted (Scots pine, Sitka spruce, Pinus contorta), reacting differently perhaps to the neglect over the past 40 years...

The alternative to an outright sale to an external buyer seems to be to harvest the trees now, or in the next few years, replant, and leave the result to one's grandchildren in 70 years' time. How would one set about this, and would it be sensible if more than one plotholder got together and collaborated in finding a firm to fell and market the timber?