Good read! There's not much of this stuff left these days. I've seen a few old drydocks in South Wales but they are usually either part of a redevelopment or if not they have none of the associated buildings or anything else of interest left such as Barry:
They got rid of loads of stuff like this in Southampton over the years, one dry dock ABP filled with dredgings even though it was listed, in the end they were allowed to proceed as long as they kept a little token part of it intact!