Former England fly-half Jonny Wilkinson believes back-up number tens George Ford and Freddie Burns need more experience at Test level.
England have opted to not include either Ford or Burns on the bench during the Six Nations so far, with Alex Goode providing fly-half cover and Brad Barritt wearing the number 22 jersey.
Ford remains uncapped but appears to be next in line behind starter Owen Farrell, while Burns has won three caps including his debut as a replacement against New Zealand in 2012.
Wilkinson, who played in four Rugby World Cups with England and won 91 caps, knows that both Ford and Burns need chances to give the national side that extra bit of security should Farrell pick up an injury.
"There is definitely back-up, but with experience, it is difficult," said Wilkinson of England's fly-half stocks.
"It is that old argument that you can't play because you are not experienced enough. How do you ever play then without giving someone their first shot?
"Building up to the 2003, we had guys like myself, Paul Grayson and Mike Catt there.
"It was nice to know we had a balance of guys who knew what was what.
"To be honest, no amount of experience will prepare you for that unknown intensity and that quantum leap that a World Cup throws into the balance."
"I'm more than confident England have the depth. I've seen quite a bit of both; I've not played against George but I have played against Freddie.
"There are young guys who understand the game who don't say they can't do certain things.
"They are saying, 'I want to play international rugby, which means I've got to make it work'.
"These guys are saying 'right, if you want me to do that, no problem, if you want me to do something else, I can do that too'.
"In the past people might have been hesitant to put their necks on the block, these guys are young, but they are up there saying, 'this is what I do'."
Wilkinson also added that England are in far better shape preparing for the RWC next year than three years ago in New Zealand, highlighting the structures and clear message from Stuart Lancaster as crucial to any possible success.
"In the years leading up to 2011, with experimentation came sways in game-plan and understanding, because the team was somehow having to fit round the player as much as the player was fitting into the team. That's not what I see now," added Wilkinson.
"I see a real connection between the players. I had the chance to speak to some of the coaches after the France game.
"I saw some of the players too though I didn't speak to them too directly, I saw them and just enjoyed the obvious unity there.
"You would have to say all that bleeds from the top.
"Stuart Lancaster has got to live his own beliefs, his own values and code of conduct, but you've also got to chose the right people and make them work for you.
"It's about building connections between players, the best teams have that and I think you're starting to see that."