Hi Rob. Just stopped for a cuppa and got side-tracked!!
I know both the design and the boat in question. Pete and I almost built a Waterwitch, in fact. They have the reputation of being rather slow - I suspect that they are generally undercanvassed - and they have a rather silly little side deck, instead of a full-width cabin, because that used the plywood sheets better. The boat was designed for home building. Heaps have crossed the Atlantic and I suspect that more than a few will have circumnavigated. I knew one in the West Indies that a couple had had for about 30 years and they brought their children up on it. They loved the boat.
If you look in PJR, you will see Redlapper, a Waterwitch with junk rig. I suspect a different sail plan might be preferred these days.
The boat you're looking at, lived a couple of jetties down from me when I lived in Mot. The owner had had her for many years and at the time - 2012 - she was in very good order. I'm going down at the end of October - I could go and have a look at her, if you'd like me to, if you can wait that long!