Give MPs a free vote on Heathrow expansion, says Justine Greening

Ex-minister says opponents of third runway should be allowed to have their say

The government must allow a free vote on Heathrow expansion plans to allow ministers and MPs to represent their constituents, the former education secretary Justine Greening has said.

Greening, a fierce critic of the plans, said ministers such as Boris Johnson, the foreign secretary, should be allowed to register their long-held opposition to a third runway without breaking collective cabinet responsibility.