I do wonder if there is a measure of positioning this to force the Thames Estuary plan but make it "Let them think they came up with it themselves".
First we have the decision to build the 3rd runway with the compulsary purchase around Sibson. Then, ooops, we find that the noise & pollution estimates have been understated. Next we find, ooops, the cost is a whopping £13bn+. Now we find, ooops again, that they forgot to state that a crash zone was right over a major motorway insection.
So now Joe Public may well be starting to think that there may be merit in a wholly new airport. "Oh alright then, if that's what you want..."
Or am I giving our leaders more credit than they deserve?