Interesting questions, RQ. I have never understood why fierce Celtic pride is considered quite so acceptable, whereas the Ango-Saxon equivalent is often derided. Perhaps its to do with the lack of a Celtic linguistic tradition, more spoken about than written down, and romanticised through myth and legend. Whereas Anglo-Saxon life was perhaps more basic, down-to-earth and, in due course, written down and recorded in their own language as they became dominant.
The little Englander, or little Briton, syndrome reflects I suppose the sometimes inward-looking nature of island communities. Difficult to reconcile that, however, with British world-wide involvements over the ages.