Jack, This is a great question. I think that, as he was Welsh and in was in Wales, the Cymru project would be the appropriate project. The British Isles project is overarching, and I think the narrower focus is best, so the Bristish Isles template should be removed. That being said, when I find a profile that fits within a project, and another project has already put its badge on that profile, I just put the project category on the profile to avoid "badge overload."
For me, the question becomes: What do you do when two or more NON-RELATED projects fit an individual? Do you put badges for each project? An example might be a person who belongs in the Black Sheep Project, but also in the Australian Convicts and First Settlers Project. Or, a specific example, (but perhaps not non-related projects), Catherine of Aragon, Aragón-160, who is thrice badged: British Isles, EuroAristo, and Notables.