Twelve months ago, it was Wales who edged a 19-12 thriller at Twickenham en route to claiming a third Grand Slam in eight years but Barritt is convinced England would win that game now because of the character and resolve that has been forged in the team over the last year.
"That resilience and the ability to win when things aren't going your way are key traits," Barritt said. "In last year's game against Wales, this team was still pretty inexperienced. There have been great stepping stones along the way since then."
The first of those staging posts was the summer tour of South Africa, when England bounced back from two brutally physical defeats to draw the third Test in Port Elizabeth.
The second was on December 1, when England buried the frustration of consecutive home defeats to beat world champions New Zealand at Twickenham and the third came in Dublin earlier in this championship, when England beat Ireland 12-6 and passed what Lancaster described as the biggest test of the character yet.
Against both the All Blacks and Ireland, England faced moments when the momentum was against them and defeat seemed likely but in both occasions they rallied to win.
They did the same against France and withstood a late onslaught from Italy last week to tee up this shot at a slice of Grand Slam history.
Despite the collective disappointment with the performance against Italy, England's confidence in their own resolve remains intact and it fuels their belief heading to Cardiff.
"It is going to be a very tough physical battle, especially with what is at stake," Barritt said. "This is a brilliant place to be. The amount of hard work that has been done since the team came together typifies what this team is about.
"We take a lot of confidence from what we have done, especially the game against Wales last year when we thought we were possibly the better team on the day. In the trip to South Africa, the experiences at the end of the autumn and in these consecutive wins, this team has learned a lot about what we need to do in international rugby. Without taking this next step, it would be a massive shame."