Quoted from http://www.baronage.co.uk/ :
'The question of the origin of the Campbells cannot, until further light be thrown upon it, be determined with certainty at the present day. It is possible that the favourite story of the genealogists may be true; they declare that the predecessors of the Argyll family, on the female side, were possessors of Lochow or Lochawe in Argyllshire, as early as 404 A.D. Of this, however, there is no proof worthy of the name. The first of the race who comes prominently into notice is one Archibald (also called Gillespic, which in Gaelic means "servant of the Church") Campbell, as likely as not, we think, to be a gentleman of Anglo-Norman lineage, who lived in the 11th century. He acquired the lordship of Lochow by marriage with Eva, daughter and heiress of Paul O'Duin, Lord of Lochow, denominated Paul Insporran, from his being the king's treasurer."
Frank Adam's book, Clans, Septs, and Regiments of the Scottish Highlands, as revised by Sir Thomas Innes of Learney in 1970, places Eva, the daughter of Paul O'Duine, Pol an Sporain, in the 13th century, but Beryl Platts agrees with the earlier version and identifies Archibald with Erkenbald, living in the reign of David I. Research into this difficult area continues, and the detailed genealogy given here begins with Sir Colin Campbell of Lochow , Calein Mor, who lived in the latter half of the 13th century and whose father, Sir Gillespic (or Archibald) Campbell may perhaps have been the Gillespic (or Archibald) who married the heiress of Lochow.
Erkenbald is the Flemish equivalent of Archibald, which reinforces John Keltie's supposition that the husband of the Lochow heiress was an "Anglo-Norman" (for until very recently most historians have treated the substantial Flemish presence in the Conqueror's army at Hastings as "Norman", and neglected the subsequent near-monolithic structure of Flemish society and influence in post-Conquest England, a substantial political force that moved north to Scotland with David I and his Flemish wife, Maud).'