Castle Mill is situated at the lowest point of Castle Hill, where it is thought that an actual castle once stood. I wasn't able to find any history or information about the mill at the time, but have since discovered that it was part of a complex of three mills. More information will be added at a later date once I've finished the article for one of the other mills.
There is another, more workaday, part of the building behind the front edifice, which I have been unable to get a clear look at and which I think is one of the two other mills...although please don't quote me on that as I haven't finished the research yet. The ground floor of Castle Mill is used by a pet food company, but the rest of the building looks quite derelict and unused.
Despite the feeling of neglect, some delightful remains include a flower basket and window box along with an old hosepipe reel hanging on the wall.
And also what appears to be pet or bird cages outside the entrance, below. Now empty.
And finally, in the photo below, another mill (known as the Old Brush Works) can just about be seen on the top right side. There will be more about that once I've finished the article and I'll put a link here when available.
Some more photos along with these can also be seen in the Photo Gallery album.