If the bidding goes 1NT P 2
which is alertable in England with every meaning {I think} but the player does not alert it then his opponents have not been misinformed. Yes, there has been a technical violation, for which a PP could be given, but the next player would not be allowed to do anything on a basis of misinformation because he has not been misinformed.
In the current case the player basically knows that 2
was likely to be alertable. In such a case he is not misinformed if he pretends he did not know. He would get no adjustment if he failed to ask, and he is not allowed to change his call.
He did not make his original call "because of misinformation" because he had a perfectly good idea what was going on. Therefore he is not allowed to change it.