Nottingham: England captain Michael Vaughan admitted there was room for improvement from his side ahead of the "ultimate test" against South Africa despite a decisive win over New Zealand here.
Victory by an innings and nine runs with a day to spare at Trent Bridge gave England the three-match series 2-0 after their six-wicket win at Old Trafford followed the drawn opener at Lord's.
But in both of these wins over the Black Caps, whom they defeated 2-1 in a three-match series in New Zealand in March, England had to come from behind after their middle-order faltered.
At Trent Bridge, they were 86 for five with the out-of-form Ian Bell and Paul Collingwood out for nought before Kevin Pietersen (115) and Tim Ambrose (67) rescued the innings with a stand of 161.
Test-best scores from tailenders Stuart Broad (64) and James Anderson (28) boosted England's total to 364.
Then swing bowler Anderson overwhelmed the Kiwi top order with seven for 43, his best first-class figures as England made their opponents follow-on.
But with a four-Test series against South Africa - whom England lead in the world rankings by just a point and who beat New Zealand 2-0 in October - starting on July 10 at Lord's, Vaughan knows England must end a run of 12 Tests without a first innings total of 400 if they are to remain competitive.
"A sign of a good team is getting out of these positions but the sign of a really good team is not getting in those positions in the first place," said Vaughan.
"There are ways to improve and the South Africa series will be the ultimate test to see where we're at as a Test team."
He said he hoped the upcoming limited overs series against New Zealand would boost the confidence of both England one-day captain Collingwood and Bell.
"Sometimes it's a good thing to just get into another form of the game and free yourselves up," said Vaughan. One quick fifty could get them into form.
"But we've won four out of five now and I think in every one of those wins, we've got better and better in each game."
Vaughan admitted the sometimes diffident Anderson could build on this man-of-the-match winning performance.
"When he's swinging it, there's not many better around than him. The key to Jimmy is being confident in himself. He has lots of ability, it's just allowing that to come out."
England could have Andrew Flintoff, who hasn't played a Test since appearing against Australia in Sydney in January last year, in their side for the opener against South Africa if the star all-rounder recovers from a side problem.
Vaughan was keen to add the Lancashire fast bowler to his attack, saying: "I'd love to have him in the team."
For New Zealand captain Daniel Vettori, whose side were polished off on Sunday by left-arm quick Ryan Sidebottom's spell of four wickets for five runs in 19 balls, this was another example of the team's inability to last the distance.
"We were able to compete for some of the time but unable to compete for a whole five days," Vettori said.
"If you look back to the last six Tests, the only time we did that was at Hamilton, which we won. It's something we've got to find a away to do."
This was New Zealand's first Test series since the retirement of former captain Stephen Fleming.
James Marshall struggled to fill his place at No3 and was dropped for the Trent Bridge match.
Fleming averaged 40 in Tests and Vettori said: "The hardest thing in missing Stephen is his runs and we need to find them from someone else."