Why? Because of circumstance. United supporters apparently sated by success, were enthusiastically embracing the unexpected appearance of underdog triumph. Watching their millionaire representatives like Wayne Rooney or Phil Jones honestly scrapping for the cause suddenly enlivened previously moribund vocal chords. Given the lead of evident effort from the pitch it seems even the modern fan is capable of getting noisy. The difference from the long mythologised old times is this: these days the fan - paying out a significant proportion of their disposable income to be entertained - requires such encouragement. This is what it takes to get noisy: a bit of effort from the players. And the fact that they are infrequently lifted to such heights at the Lane and the Bridge may well be the responsibility of those in the dressing room, rather than in the stands.