Transport secretary Geoff Hoon this morning told MPs that the Government would back the £9 billion expansion of the west London airport, which includes a sixth terminal.
The plan will see a 2,200 m long third runway built by 2020. It will run parallel to and north of the existing runways.
More than 2,000 people will lose their homes when the village of Sipson is demolished for the project.
But the pro-expansion lobby argues that Heathrow is already full and that the economy of London and the UK will suffer unless there is expansion of the country's biggest airport.
In unveiling plans for rail links between Heathrow and St Pancras, Mr Hoon also said he saw a "strong case" for a new high speed rail hub at Heathrow and had created a new company to explore the creation of a high speed line between London and Scotland.