Original: According to legend , Achaius , King of Scots ( possibly coming to the aid of Óengus mac Fergusa , King of the Picts ) , while engaged in battle at Athelstaneford with the Saxon King Aethelstan of East Anglia , saw in the heavens the cross of St Andrew .
Simplified: One story says that Achaius , King of Scots , was fighting King Aethelstan of East Anglia and he saw cross of St Andrew in the sky .