 Ireland march on towards a possible Grand Slam after inflicting a thumping defeat on a misfiring England.Four penalties from Jonathan Sexton and a second-half try from centre Robbie Henshaw opened up an unbridgeable gap which accurately reflected the one-sided nature of what was expected to be a tight contest.England were outplayed in all departments, starting slowly, consistently second-best at the breakdown and all too fallible under the high ball until a late rally.