Bye Bye Bicycle said:It's not that hard to be outstanding in Ireland's or GB's junior scene. Dunbar is not that good, his national competition is just pretty weak. I don't see him in the World's top 10.
You certainly get a small pond factor in Ireland. The one guy who is good in any age group is usually way better than anyone else. Less so in Britain these days. The two together represent a big enough talent pool for being the best by miles to be reasonably significant. Of course, how significant is hard to know, given the absence of a real international season for kids.
Of course even being a world class junior is of very limited predictive value anyway.