Despite delighting a packed Twickenham crowd Lancaster was quick to point out that tougher tests lie ahead this autumn.
He told Sky Sports News: "It was good to get the win. We struggled a bit for 10-15 minutes. We didn't convert every opportunity but we were pleased with the opportunities we did take.
"It was a good start but we recognised the quality of the opposition that is coming around the corner. We will have to step up a couple of levels next week.
"Next week against Australia and the week after and the week after that we are going to have to be more clinical."
England take on Australia next Saturday before completing their Test fixtures for 2012 against New Zealand and South Africa.