Northampton lead Prem charge but history shows title defence will be no simple task | Robert Kitson

<p>Boosted by retaining Henry Pollock, champions are eager to keep improving but a revitalised Saracens and Exeter should push them all the way</p><p>It used to be simple. Win the Prem once and people would assume it was just the beginning. At various times no one could dethrone Ba