July 12, 927. Æthelstan's great meeting at Eamont
Æthelstan's title becomes Rex Anglorum, King of the English
The Anglo-Saxon Chronicle records that in this year Æthelstan succeeded to Northumbria, and that he brought under his rule all the kings of the island, Hywel of the West Welsh, Constantine of the Scots, Owain of Gwent, and Ealdred, son of Eadwulf of Bamburgh. At a meeting at Eamont (in Cumbria) on 12 July they made peace with pledge and oaths. William of Malmesbury in the 12th century mentions a meeting at Dacre where Constantine of the Scots and Owain of Strathclylde pledged peace to Æthelstan, so it may be that Owain of Strathclyde should be added to the Eamont list (GRA, ii.134.2).
Michael Lapidge has demonstrated that a Latin poem about Æthelstan, the Carta Dirige Gressus, was composed in the immediate aftermath of the council at Eamont (see Lapidge, pp. 90-93). The poem agrees with the triumphal tone of the Chronicle entry, noting that England was now "made whole" (perfecta Saxonia), and there are other indications that the victory of 927 was seen as a turning point. Æthelstan's coins after 927 often bear an abbreviation of the style Rex Totius Britanniae, "King of the Whole of Britain", and coins in Æthelstan's name are minted all over the country, including Northumbria. Charters also show the change to the perfecta Saxonia: the king's style changed from the Rex Angul-Saxonum, "King of the Anglo-Saxons", used by Alfred and Edward and Æthelstan in his earliest years and implying rule over the West Saxons and the Mercians, to the simpler Rex Anglorum, "King of [all] the English". In the early 930s, the style expanded to "King of the English and by Grace of God Leader of all Britain". The witness-lists of some charters from 928 to 935 include the attestations of Welsh and Scottish rulers (Hywel Dda of Dyfed, Idwal of Gwynedd, Constantine of the Scots), who appear as sub-kings (subreguli) of Æthelstan.
C. Blunt, "The coinage of Athelstan, 924-939", British Numismatic Journal 42 (special vol., 1974), pp.35-160
M. Lapidge, "Some Latin poems as evidence for the reign of Athelstan", Anglo-Saxon England 9 (1981), pp.61-98
R. Mynors and others, William of Malmesbury: Gesta Regum Anglorum (Oxford: 1998)