Roby's break created a try for Gidley, Gardner crossed for his fourth, and easiest, after Eastmond's lofted kick found him completely unmarked, Lomax raced in for a try, Roby scampered over at the corner and Dixon cashed in on a defensive mix-up.
But they got off to the worst possible start when keeper Kasper Schmeichel raced out after a long pass from Madjid Bougherra only for Charlton striker Varney to beat him to it and lob the ball into the empty net from 20 yards.