Former World Cup winner Lawrence Dallaglio believes an England triumph on Saturday would be the greatest achievement in the history of the tournament.
After beating Australia and New Zealand in the knockout stage, England need to take the third southern hemisphere scalp of South Africa to lift the Webb Ellis Cup for the second time.
Dallaglio says that an England's first "Southern Slam" would be the greatest performance by any of the winners to date.
"If they were to beat Australia, New Zealand and South Africa I don't think anyone could argue that that would be the greatest World Cup achievement ever," said Dallaglio.
"You know you have to win seven games to win the tournament – normally two of them end up being quite tough but to have three back to back is another level. The only way to get respect from the people it's hardest to get it from is to beat them."
England also beat the fourth Rugby Championship team and 2015 semi-finalists Argentina in the pool phase.
Dallaglio was a key part of England's back row when they triumphed in 2003 and he came off the bench in their 2007 final defeat by South Africa. The former captain said last Saturday's triumph over the All Blacks was undoubtedly one of the best from his country.
"It was very, very impressive," he said. "One of the all-time great performances, especially when you factor in the occasion, what was at stake and the quality of the opposition.
"The really impressive thing was there was a game plan that was clearly put together and it was executed by the players from minute one to the end."
Dallaglio said Saturday's performance was not out of the blue but the culmination of the last three years of development. The team have a "core of serial winners" - used to success for England and for Saracens. But what they delivered in the semi-final was still of a "different dimension", he said.
"What was so wonderfully refreshing was the courage they played with," he said. "They had the mindset of 'we're not going to just beat you, we are going to totally beat you'."
Much as he enthused about the performance, Dallaglio warned fans to temper their expectations of a repeat in Saturday's final against a South African team who, as they showed in their semi-final victory over Wales, will bring a different threat.
"Nobody should expect England to replicate that," he said. "It won't be easy and it won't be pretty. South Africa are very proud, very strong and will be a tough nut to crack. They're not easy on the eye but they don't need to make an excuses for that."
Dallaglio said the Springboks stick to a tried and tested pattern when in their own half but allow themselves a little more freedom when on the offensive over the halfway line.
"It works for them – it's pragmatic - not pretty, but effective," he said. "A lot of people predicted they would win the World Cup so it's not a surprise they are still here – even the pool game they lost to the All Blacks was a lot closer than the score (23-13) suggested. "I think that game showed that to beat them you have to get out in front, then that structured approach in their own half gets challenged."
Dallaglio said that if England do triumph on Saturday he does not think there would be a repeat of the post-World Cup slump that overcame them in 2004 when they went from "best in the world to worst in the world".
"We planned for winning but not for success afterwards," he said. "This group won't have that as they are still very much on that journey. The All Blacks set the bar so high and that's what motivated Eddie Jones and the players. Now it's England's turn to try to keep driving those standards."