England finished second to Ireland by a difference of six points, falling short despite an impressive 55-35 defeat of France on Saturday.

"Four years as runners-up is not acceptable and we are not happy with how that came about," Ritchie said.

"If you go back through history, bearing in mind a lot of things, we should be, as a country, winning more in terms of Grand Slams, Six Nations championships, other things."

An opening win in Wales stoked belief, but the home defeat of Italy was followed by a loss to Ireland in Dublin which ceded the championship initiative.

England finished with wins over Scotland and France, but still Lancaster is without a tournament win after four attempts.

Lancaster is under contract until 2020 and there is no suggestion his position as head coach is under pressure, but Ritchie insisted England had the chance to win the tournament.

"We had opportunities," Ritchie added.

"Let's be clear - entirely in our control. It was stuff that was in our own hands.

"The Irish deserved the win because of what they did over the five matches.

"We did not do enough over the five matches. There's no point in bleating about it.

"We simply didn't take opportunities, didn't do what we should have done, were not clever enough during parts of the game in order to deserve to win.

"'We're developing, this is a development opportunity' - I don't take that. I don't think we're in a development phase.

"We should be going into every game, doing our utmost to win and to win well.

"We've got the resources, the talent, the ability. Saturday was a fantastic example of that.

"We've got to make sure we come out for the World Cup and deliver."

England face Wales and Australia in World Cup Group A, which kicks off against Fiji at Twickenham on September 18.

"Are we capable of winning? I think, hope, believe fervently that we're capable of winning," Ritchie added.

"The thing that strikes me about elite world sport, margins are so small.

"I'm absolutely sure when we get to the World Cup it's going to be small margins that will make the difference between winning and losing. It usually boils down to who delivers on the day.

"Are we in the frame enough to win it? Yes, I think we've got enough talent, I think we've got enough talent now, I think we'll have more talent coming back in when we get to September and I've got to think and believe - and I know the team and Stuart believe that - that we can win this.

"We should be able to win it. Will we do it? Then that depends on our application and execution doing the games. It's frankly as simple as that."