It has to be said that the negatives of these photos taken back in 1980, are not in the best of condition. They were processed by a local chemist (probably Boots) and it looks like they weren't properly fixed.
It was not long after this that I moved to the envelope service of professional photo-finishers Colab Ltd (who, after a torrid time during the change to digital, now trade as One Vision Imaging). The negatives they produced have survived a lot, lot better.
It then changed hands a number of times, with each owner stripping more and more material from the ruin. Eventually it was sold to William Aislaby who incorporated it as a romantic ruin in his Studley Royal Estate.
For opening times, admission prices, etc. please see the National Trust's official site.