Heathrow Airport chief executive Colin Matthews says: "We say a hub (airport) matters but actually does it matter to the country as a whole?
"The economic analysis we published today suggests it really does."
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A group of disabled activists threw toys and balls at him as he entered the conference.
A wet start to the week and the unsettled weather is set to continue over the next few days.
The Airports Commission backed a new runway in its final but the Chancellor appears to have set out a new timetable for the actual decision.