Part of our successful submission was the statement "By their efforts they have re-established a tradition of milling and millwrighting at Acorn Bank." Since then we have continued to develop our skills and increase our experience.
I was therefore very interested recently to discover the Heritage Crafts Association (President HRH The Prince of Wales) which publishes lists of endangered crafts. Millwrighting is listed as Critically Endangered (see https://heritagecrafts.org.uk/millwrighting/) as there are so few practitioners.
That means, as far as I can see, that we old volunteer millwrights are ourselves suitable subjects for preservation by the National Trust!