Expansion at Heathrow has not already been favoured ahead of the Davies Commission, which is due to publish its interim report tomorrow (December 17th).

This is according to transport minister Patrick McLoughlin, who spoke on BBC 2's The Andrew Marr Show the government was not pushing for a third runway. Whatever options the report considers, the airport will not be developed until the current parliament ends in 2015.

Mr McLoughlin said: "I want to see what their interim report is this week and their final report in 18 months' time and then we'll be able to say which is the right way to go forward."

The main competition so far is between Gatwick, Heathrow and Stansted. Former transport secretary Steve Norris told the London Evening Standard he now prefers an additional runway at Gatwick compared to Stansted, because it is more ready for the upgrade.

However, he believes Stansted can support more runways in the long run.

Meanwhile, Boris Johnson has been trying to prove the viability of his Thames Estuary Island concept, meeting with the report's chair Sir Howard Davies. If successful, 'Boris Island' would be one of the first new airports built in the UK in over 20 years.