The Azzurri also emerged relatively unscathed from the sin-binning of scrumhalf Edoardo Gori for pulling back Flood off the ball and the loss of prop Martin Castrogiovanni, who injured his left leg.
England would have trotted off to the dressing room frustrated and disappointed, but things just got worse.
Luciano Orquera canceled out an early second-half penalty by Flood and then delivered a perfect cross-field kick behind the out-of-position Chris Ashton right into the path of McLean, who dotted down in the left corner. The conversion was missed, but Italy’s tails were up at just 15-11 down.
England captain Chris Robshaw dropped a high kick under no pressure. Flood’s kicking out of hand became aimless. Tackles were missed. England, suddenly, were a shambles.
“I felt we let our control slip — Italy pushed us right to the end,” Lancaster said.
Orquera missed a chance to put Italy just one point behind as he skewed a penalty wide, while Flood’s sixth of the afternoon — in the 62nd — gave England a seven-point cushion they would never lose.
However, only a lack of control at critical moments denied Italy a famous result.
Wales will be uplifted by what they saw in London.
“Four from four isn’t a bad place to be in,” England defense coach Andy Farrell said. “When it comes down to the last game, form goes out of the window.”