Lovely review of Arthur, Andrew. The last word on Pelagius is in Colin
McEvedy’s PENGUIN ATLAS OF MEDIEVAL HISTORY, p.26:
“Pelagianism, the native British development [i.e. of the Monophysite
heresy], rather lost its point when the legions left and the heathen Saxon
became the antagonist, but in its concern with this life rather than the
next it seems temporarily to have tapped a deep stream in the insular
character.”