By the power of his sword arm, his dragon fleet and his sheer personality, Somerled Norse Slayer carved an enduring name for himself in Scottish legend.   Inheriting his father's shattered thanedom in Argyll in the twelfth century, he enlarged it by courage, initiative, military shrewdness and diplomacy. For decades his navy held the balance of power in the northern seas, and it was he who cleared the Vikings out of the Hebrides.   Set against the romantically celebrated West Highlands and Western Isles of Scotland, the story of the conquests and courage of this hero king is a living tribute to a renowned legend. 'Through his imaginative dialogue, he provides a voice for Scotland's heroes' Scotland on Sunday