As part of a wider cabinet reshuffle, Conservative Prime Minister David Cameron named Patrick McLoughlin as transport secretary, replacing Justine Greening who had been strongly opposed to any expansion of Heathrow Airport.

Britain's Conservative-led coalition government had ruled out building a third runway at London's capacity-constrained Heathrow before the next election, in part to appease the junior Liberal Democrat partners and boost its green credentials.

But the issue has returned to the agenda in recent months with the economy stuck in recession and critics of the policy arguing that increased flights could boost growth.

London Mayor Boris Johnson, who is pushing for the construction of a new airport in the Thames Estuary instead of expanding Britain's biggest airport Heathrow, slammed the decision to remove Greening.

"There can be only one reason to move her - and that is to expand Heathrow airport," said Johnson.

"Nearly a third of the victims of aircraft noise in the whole of Europe live in the vicinity of Heathrow. Now it is clear that the government wants to ditch its promises and send yet more planes over central London."

Greening, who lasted just 10 months as transport secretary, was a staunch opponent of a third runway at Heathrow and had come under pressure to change her stance in recent weeks after a succession of senior Conservative ministers called on Cameron to rethink his opposition to a third runway at Heathrow.

Just last week she had threatened to resign if the government gave in to pressure to expand Heathrow.

McLouglin, a former coalminer and agricultural worker, has experience in aviation, having previously served as a minister in the Department for Transport (DfT) under Margaret Thatcher's government.

Government insiders say Cameron and finance minister George Osborne have an open mind on expanding Heathrow, compared with Greening who was unlikely to change her position given her Putney constituency is under the Heathrow flight path.

Several options are being considered to increase the southeast of England's strained airport capacity: a third runway at Heathrow; a second at Stansted northeast of London, or a new airport in the estuary of the river Thames.

"The industry wants the opportunity for growth which they have been denied," said Davy stockbrokers analyst Stephen Furlong.

"Maybe the government are hedging until the next election (in 2015) but air traffic is projected to double in the next 20 years and if Britain's main airports are full, businesses will go elsewhere and the UK and London will suffer."

Heathrow operator BAA, owned by Spain's Ferrovial (FER.MC), believes the airport is falling behind European rivals like Paris, Frankfurt and Amsterdam in the battle for lucrative routes to China because of the constraints on growth.

Greening was deeply unpopular with airline bosses such as IAG's (ICAG.L) chief executive Willie Walsh and Ryanair (RYA.I) boss Michael O'Leary.

At a news conference in London earlier on Tuesday O'Leary said "the sooner she (Greening) is gone the better - I hope the next one is better."

Greening will become international development secretary. (Reporting by Rhys Jones; Editing by Steve Addison)

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