The Twickenham result dealt a severe blow to England’s hopes of being top seeds for the 2015 Rugby World Cup when the draw is made in London on December 3.
Ashton is thankful the tournament on home soil is still three years away because England need that time to sharpen their cutting edge.
England hung in as Australia dominated the first hour and Stuart Lancaster’s men then bossed the final quarter, but they could not convert any of that pressure into points.
On four occasions, the first being with 22 minutes left in the match, captain Chris Robshaw opted not kick penalties at goal in search of a try that did not come.
“I think we cost ourselves the game. We had enough possession in their 22 and we just didn’t take our chances,” Ashton said.
“I think the right decisions were made from those penalties (to go for touch or quick taps). I thought we had them but we just couldn’t find that finishing pass.
“Toby Flood tried to find me through the back and if the pass had gone to hand I would have been through a hole. And then Thomas Waldrom dropped the ball over the line.
“You have to take your chances. Our attack was better (than it was in last weekend’s 54-12 win over Fiji) but we are lacking that clinical edge.
“We put ourselves in a position to win that game and that was the frustrating thing.”
Ashton’s frustration on the field was evident – particularly when Manu Tuilagi ignored him on the overlap and ran straight into two defenders.
Tuilagi had done something similar to Charlie Sharples at the end of the first half but got away with it when he had just managed to score in the corner.
That try came minutes after Nick Cummins had scored his first for Australia and it gave England a 14-11 half-time lead against the run of play.
Australia were the smarter attacking side with the variety offered by Kurtley Beale and Berrick Barnes a lesson to England about how to use twin playmakers at fly-half and full-back.
The Wallabies edged the scrum battle until Joe Marler was replaced by Mako Vunipola and, in openside flanker Michael Hooper they had the man of the match.
There was some debate about whether Tuilagi had actually managed to ground the ball on the whitewash but the try was given by TV official Jim Yuille, who had a busy day.
Yuille was asked to adjudicate on potential tries from Wallaby prop Ben Alexander, where the pictures were inconclusive, and later from Waldrom, where they were not. Both were ruled no try.
Australia turned the screw after the interval with Barnes kicking three penalties in quick succession to win the clash.