It's easy to forget, as we contemplate today's British monarchy drained of its once magical aura, that kingship was one of the great medieval institutions. And English medieval kingship again was a creation of the tenth century (we even still use their coronation order!). This was the institution on which the ultimate responsibility for social order rested. And it was the kingship of Alfred of Wessex and his successors that gave substance to the English state.
The Anglo-Saxon kings who were most praised and best remembered were kings whose power base wasn't just in southern England. Athelstan grew up in the Midlands and presumably spoke with a Midlands accent, even though he was the son of a southern king. Although men like Athelstan and Edgar, his brother, were kings of Wessex, their interests and their friendships needed to be more national.
Success as a medieval king depended on maintaining a delicate approach which paid close attention to local sensibilities. You can see this particularly well in the law codes. Edgar's code, issued in 962-3 for example, specifically talks about:
'...measures common to all the nation, whether English, Danes, or Britons, in every province of my kingdom, to the end that poor man and rich may possess what they rightly acquire...'