England coach Eddie Jones insists his side still have room for improvement following their 25-21 victory over Wales in the Six Nations.
The 2003 world champions have won all four of their matches since Jones succeeded Stuart Lancaster as coach, and they remain on course to secure their first Grand Slam success in the Six Nations in 13 years.
Saturday's result at Twickenham also secured England the Triple Crown, but the result should have been more comfortable for Jones' men, who led 25-7 with just 20 minutes remaining in the match.
The Australian believes the victory emphasises just how far his side has come since their embarrassing pool stage exit from last year's World Cup on home soil, but he admits the last 20 minutes show that there is still room for improvement within the team.
He said: "England played Wales in the World Cup in September. If you'd said five months afterwards we'd be ahead 25-6 (actually 25-7) after 60 minutes against Wales, then you'd be pretty happy. We won the game 25-21, and we've won.
"What was significant was our first 60 minutes. I thought we played really well, with a lot of precision, were tactically smart, physical. In the last 20 of the game, which is a good learning experience for us - we had to defend with 14 men at the end - but to get a win over Wales."
England will be looking to secure the Grand Slam when they take on France at the Stade de France next Saturday, but have lost on both visits to Paris since their narrow 24-22 success in 2012.