England's target is to become the world's top-ranked team, captain Dylan Hartley revealed after his side made history by beating Australia 23-7 in Melbourne to record a first series victory Down Under.
Hartley, who became England's most-capped hooker by making his 74th appearance, went over in the first half and Owen Farrell scored 17 points as Eddie Jones' men followed up their first-Test win with another victory at AAMI Park.
The skipper hailed his team's performance, but insisted there is more to come from the Grand Slam champions.
"We're a team that wants to improve and be number one in the world," the inspirational Hartley told Sky Sports.
"We've still got one more game next week. We know Australia are a formidable team. We'll enjoy this bit of history, but the message is we'll go again.
"The key thing from last week was defence - Australia are one of the best in the world with the ball in hand. It was important we got some good shots in. We took the onus on ourselves to defend better."
Coach Eddie Jones added that England will not be "satisfied" unless they go on to complete a whitewash in next weekend's third Test in Sydney, although he described claiming the Cook Cup as a "great result for English rugby".
"We had to defend and play off scraps. That's how we executed the game," Jones told Sky Sports. "But we're not going to be satisfied unless we win 3-0.
"I thought we'd get a bit more out of the set-piece, but with the scrum collapsing all the time it was difficult to get an advantage.
"I thought Chris Robshaw and James Haskell made a six and a half - we're going to have to change the numbering system.
"This is a great result for English rugby. It's for the supporters. You have occasions in your life when you're lucky and when you coach good players you're lucky."