 England overcame both a dangerous Australia and their own shortcomings to grab a precious southern hemisphere scalp and get their autumn campaign off to a winning start.Opportunistic second-half tries from skipper Chris Robshaw and fly-half Owen Farrell saw them overturn a seven-point deficit after Matt Toomua's try had seen them in trouble at the break.Farrell kicked two penalties and added both conversions after earlier missing three kicks as the home side's superior scrum and forward power in the loose made up for a disjointed display elsewhere.