Photo: Mike Hewitt/GETTY IMAGES Former Arsenal vice-chairman David Dein has admitted that his failure to prevent Ashley Cole from joining Chelsea was one of the biggest regrets of his career. (adsbygoogle = window.adsbygoogle || []).push({}); Dein, who was Arsenal's vice-chairman for 24 years between 1983 and 2007, oversaw some of the Gunners' most glorious title-winning years and