There comes a time in every government’s tenure when we finally see them for what they are – that the slick messaging and spin can no longer hide the flawed natured of the policies.

Today is one such day for the British government. There comes a time when a government makes decisions that will define their term in office. Today is one such day.

For years, the British Labour Government has tried to portray itself as a leader in the battle over climate change.  Take one just small example, just days before the Bali Climate Change conference in late 2007, Gordon Brown, the UK Prime Minister, gave a speech to the foreign press association on climate. He called for “vision and determination” from world leaders to rise to the challenge of climate change.

“Our mission is, in truth, historic and world changing – to build, over the next fifty years and beyond, a global low carbon economy. And it is not overdramatic to say that the character and course of the coming century will be set by how we measure up to this challenge.”

Well Gordon you have failed. For once a Government could have been bold. It could have stood tall and announced that finally, yes the policies would match the rhetoric. But alas no. Today Brown will pander like a poodle to the powerful aviation lobby and announce a deeply divisive, controversial plan to build a third runway at Heathrow Airport.

We should also not forget that this is not just a fight about climate. It is a also a fight about people’s homes and communities. Some 700 homes will have to be demolished to make way for the runway, which will increase the number of flights using Heathrow from about 480,000 a year now to 702,000 by 2030.

The environmental correspondent for the Independent, Michael McCarthy sums it up rather succinctly: “At a stroke Gordon Brown destroys his environmental credibility and that of his Government … UK greenhouse gas emissions from aviation are rising faster than those of any other sector. To sanction a policy which actively promotes their expansion, in the very year when the international community is desperately trying to put together a treaty to cut emissions back hard, and Britain has officially adopted the target of cutting back its own emissions by 80 per cent, is political nonsense.”

The sad truth is that it is nonsense to argue that you can have credibility on climate change at the same time as allowing Heathrow to expand. An expanded Heathrow would become the single biggest emitter of CO2 in Britain, and will become a symbol of the Government’s ineptitude on climate.

The goahead for the third runway goes against previous promises made by the government. The Government Inspector, Iain Gildwell QC, who passed Terminal Four at Heathrow said: “this is the last major expansion of the airport”.  But that tunred out to be a lie.

“After Terminal Four they promised they would not need another terminal, and then almost immediately they put in the application for Terminal Five” argues Labour local councillor Ruth Cadbury. “They told us at the end of the Terminal Five inquiry, that that is it -no more expansion, and then the said they needed a third runway which will need a new terminal. We never trust them and their promises, because they always renege on them.”

After today, you know that you cannot trust Gordon Brown on climate.