The difference with England is that it's historical circumstances have been significantly different. The true natives of the British Isles were people like the Celts (Scottish, Irish, Picts) and the modern day Welsh. Then multitudes of Germanic people invaded like the Angles, Saxons, Danes, Vikings, Franks etc. Initially these people warred with each other (e.g. Anglo-Saxons fighting the Vikings) but then they realized they spoke a common Germanic language which ultimately led to peace and hence development. All the while people like the Welsh were pushed away into a corner (btw, Wales means foreigners in Germanic languages). This occurred over 1000 years ago and the English have developed a very elaborate sense of unity since then.