Flood, 26, has been England's first choice since replacing the peoples' favourite Jonny Wilkinson at the end of the 2010 Six Nations.
But the Leicester fly-half, despite his key role in transforming England's fortunes, has always been aware he is swimming against the tide of public affection.
Wilkinson made an impressive pitch to reclaim the England 10 jersey with a man-of-the-match performance against Wales in last weekend's first warm-up international.
Flood will get his opportunity to respond in the return match at the Millennium Stadium this weekend - but admits he will be on trial for his World Cup place.
"I don't think I've ever been in charge of that 10 shirt," said Flood.
"It has always been hugely difficult for me to have it. There will be 58million people in England who probably think I shouldn't be in charge of it.
"The scenario has always been that Jonny, given his opportunity, will have a standout game and he did that.
"To me it is nothing new and I have just got to shrug my shoulders and get on with it. The nice things is there is a guy who is driving you hard.
"Whenever you play for England you are always on trial. You have got the responsibility of playing for your country. It is always a high-pressure game so nothing really changes.
"The guys have played well and the team have won a game. There is a massive responsibility on us to make it two from two this weekend."
Flood was Wilkinson's protege during their days at Newcastle but broke out of his shadow once and for all over the last 18 months, playing an influential role in England's resurgence.
Wilkinson was dropped after England's bore draw against Scotland at Murrayfield. Since then, Flood has helped them beat Australia twice and rise to fourth in the world.
But Wilkinson will forever be the hero at Twickenham and England fans still reserve their biggest ovation for the man whose drop-goal won the 2003 World Cup final.
"It is the history he's had playing for England. He has been a stalwart of the England side for a long time, and someone people respond to really well," said Flood.
"All I can do is concentrate on playing as well as I can every time I have a chance. I know he's around but it is the same for everyone in the squad, there is competition in all position."
Although rivals, Flood and Wilkinson have remained friends and they are both committed to improving each other for the benefit of England.
"The good thing is we have hung out for a long time," said Flood.
"We are good mates so we can sit and have a chat about the game and scenarios.
"We are in a situation where Charlie (Hodgson), Jonny and I will sit down and discuss things we can improve on. There is a good atmosphere where we can share information."
Flood was in imperious form as England opened their Six Nations title campaign with a 26-19 victory over Wales at the Millennium Stadium in February.
At that stage, Flood and Ben Youngs were cemented in as England's first-choice half-backs in a team playing expansive rugby - but by the end of the tournament doubts had begun to emerge.
Ireland neutered them in Dublin and England fell to a heavy defeat which cost them the Grand Slam. It was a sobering lesson.
England coach Mike Ford explained last week how the focus since Dublin had been on improving their game management, something Wilkinson did well against Wales last weekend.
Wilkinson also offered a timely reminder of his ability to keep the scoreboard ticking over with two decisive drop goals, a vital quality during in World Cup rugby.
But Flood is now ready to prove his own point. He has had an extra week's preparation after Johnson decided to rotate his squad.
"It is going to be incredibly intense at the Millennium Stadium and the crowd is always amazing. The way the players respond to that is always a massive challenge," said Flood.
"I was told a couple of weeks ago I wouldn't be playing in the first game. We have done a lot of training so it should be good."
"Of course we want to go there and win, we are want to gain some momentum. We are technically on the road for the rest of the tournament."
Johnson will finalise his 30-man World Cup squad on August 22. England play Ireland the following Saturday and then kick-off their World Cup campaign against Argentina on September 10.
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