Inside centre has been a problem position since the retirement of Will Greenwood in 2004, with England struggling to find a player who offers the right balance of guile and grunt.
"It is a real key position," said England's attack coach Brian Smith.
"You want someone who's got good distribution, ideally a kicker but if you look globally now at the shape and size of 12s they've also got to have some bump.
"You want another organiser but also a ball carrier and he also has to be a big defensive player.
"If you play a quick back three like England you need to get your punch from midfield so ideally you are looking at your 12 to be the perfect player.
"It's very difficult to have the complete game, there are not many in the world who do."
Without a player in the mould of Ma'a Nonu or Sonny Bill Williams available, England have ended up choosing between the two extremes.
They have trialled the likes of Olly Barkley and Shane Geraghty but concluded both are too light defensively, despite their creative abilities.
The need for "bump" has prevailed - but Smith admitted England are yet to hit upon their preferred midfield combination as they begin preparations to face Romania on Saturday and then Scotland.
"Through the warm-up games we've used the squad. We've got to make that call as to now do we start to hone in on our best XV or do we keep trying to rotate the squad?" said Smith.
"That's a decision we probably need to get our heads round in the next week."
Mike Tindall moved to inside centre to accommodate Manu Tuilagi for the wins against Ireland and Argentina, edging Shontayne Hape out of the team.
But the former rugby league star issued a reminder of why he was England's first choice for their Six Nations victory with two tries and a strong all-round performance against Georgia.
"Mike brings a lot of things to the party. He's a very good communicator. His performance with Manu in Ireland was outstanding," said Smith.
"That's been a good combination for us. It's nice Shontayne chipped in with a couple of tries and a solid performance because we need competition within the group.
"He's the most criticised player since I've been with England and some of it's been over the top.
"He's put his hand up in big games, he's been outstanding for us when we were under a lot of physical pressure and when you're playing big, powerful teams you need players who are prepared to put their bodies on the line.
"I'm glad he scored a couple of tries, though I don't think it was a complete performance by any stretch of the imagination."
Smith did not rule out pairing Toby Flood and Jonny Wilkinson together, although without another fly-half in the squad that would be a risky move.
"They've played side by side a few times and it's an option we've still got up our sleeve," he said.
"We would get two distributors but we lose a bit of physically there. We've also got others in the group here who can go into that role."
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