Heathrow third runway: backers fear game may be up

Government blames environmental concerns for delay in making a decision, but few take that at face value

So is it the environment, or plain old politics? Heathrow said it was confident it could meet the government's environmental criteria for a new runway - although it has yet to be told what green hoops it now needs to jump through.

Sources in the Department for Transport say concerns about air quality - and the threat of legal challenge if they are not addressed - are real: there is work to be done to ensure the government meets European Union limits on pollution and this new "period of reflection" would allow it to incorporate new data on vehicle emissions and update the Airports Commission modelling.