Captain Dylan Hartley admitted England were "not quite there yet as a team" after Ireland denied Eddie Jones' men a second successive Six Nations Grand Slam on Saturday.
Ireland triumphed 13-9 in Dublin as they also prevented their visitors from picking up a record-breaking 19th successive Test win, ending the run at 18, just as they did to New Zealand in November.
And Hartley concedes that, despite his team's remarkable run since their dismal showing at the 2015 Rugby World Cup, England - who wrapped up the Six Nations title by thumping Scotland last weekend - have plenty of room for improvement.
"We've got lessons to learn today," he told ITV. "We set out to win the tournament and we've done that but we're obviously disappointed not to win this final game because we had high hopes and high expectations of ourselves.
"It goes to show we're not quite there yet as a team.
"But full credit to Ireland. They put us under unbelievable pressure today and they gave us one hell of a Test match, so credit goes to them."
Discussing England's performance at the Aviva Stadium, Hartley added: "I think it was negative upon negative - we seemed to back up every error with another error and it put them in good field position and they executed well.
"We're not the finished article and this will keep us grounded. There's plenty of work to do but full credit to Ireland today."