England manager Martin Johnson has launched a vigorous defence of Jonny Wilkinson and blasted critics for working to their own agenda.

Wilkinson's position at fly-half has come under scrutiny following England's uninspiring 17-12 victory over Italy on Sunday. England's World Cup-winning scrum-half Matt Dawson claimed Wilkinson's inability to manage a game and react to situations off the cuff is being exposed without experienced decision makers around him.

"I don't agree with the criticism. Jonny missed a few kicks and suddenly everyone is calling for his head, which I find pretty disappointing and surprising," Johnson said.

"No-one is undroppable, no-one ever has been. But is it Jonny's fault we didn't convert our line breaks? No, it's a team thing. It has become the vogue to have a pop at Jonny. It is not always right or fair and I think some people are using it for their own agenda but that is the world we live in."

Wilkinson, 30, has only ever been dropped twice by England, for Paul Grayson in the 1999 World Cup and Danny Cipriani in the 2008 Six Nations.

And despite stating that no player is guaranteed his England place, Johnson gave no indication he is planning a change at fly-half.

Wilkinson's understudy Toby Flood is set to be released to play for Leicester this weekend, having been the only unused replacement against Italy in a game crying out for an injection of fresh ideas.

Whatever perceived weaknesses there may be in Wilkinson's game, Johnson insisted selection for any player has to be based on the whole package he brings to the team.

Wilkinson, who has won 75 caps for England, is the leading points scorer in the history of world rugby and his defence is arguably the best of any fly-half.

"You have players who are not in the team who are potentially better at some areas of the game than guys that are in the team. You have to weigh up that overall impact," Johnson added. "I think Toby has been playing well. We have good depth in that position. We are lucky to have two world-class players at 10."