Opponents to the Government's support for a third runway at Heathrow airport will present their cases at London's High Court today (March 11).

Monday marks the start of two weeks of proceedings whereby five legal challenges to the proposed expansion of the airport will be presented to the High Court before Lord Justice Hickinbottom and Mr Justice Holgate.

A broad coalition of regional councils, residents, environmental charities and the mayor of London Sadiq Khan are fighting a legal battle against the Government's decision to approve the building of a third runway at Heathrow airport.

The case is being brought against Transport Secretary and Epsom and Ewell MP Chris Grayling by local authorities and residents in London affected by the expansion.

They're being supported by environmental groups including Greenpeace, Friends of the Earth and Plan B.

The coalition are claiming that the National Policy Statement (NPS) setting out the Government's support for the project failed to deal sufficiently with the impact on air quality, climate change, noise and congestion the plans are expected to entail.

Rob Barnstone, Coordinator of the No 3rd Runway Coalition, said:

"Heathrow expansion was wrong 10 years ago and is wrong now. Not just for people around west London but for the whole of the United Kingdom.

"Heathrow expansion is not fit for purpose and will only deliver toxic air-quality for Londoners, a failure to meet our national climate change obligations, no long term economic benefits for the UK..."

The Press Association (PA) reported that "scores of demonstrators" had gathered outside the High Court in anticipation of the opening of the hearings, including several prominent politicians.

Labour Shadow Chancellor John McDonnell said that he had been opposing expansion plans at the airport for over three decades and cited climate change as the reason why.

Mr McDonnell said he had: "...been involved in the campaign against Heathrow since the early '80s".

"Over that period of time, we have discovered the implications of air pollution and noise pollution...the campaign has gone from a 'nimbyist' campaign to one that is about climate change and saving the planet".

"This is an iconic battleground in terms of climate change."

Environmental campaigners also echoed the pressing concerns regarding carbon emissions and climate breakdown.

John Sauven, executive director of Greenpeace UK, said: "The climate minister has admitted we're in the grip of a climate emergency. The environment secretary has declared air pollution one of the biggest threats to public health in the UK.

"So how can ministers justify building a runway that's bound to make both problems much worse?"

Approval for the proposals passed through the parliament with a majority of 296 in a House of Commons vote last month.

Mr Grayling said the new runway would set a "clear path to our future as a global nation in the post-Brexit world".

A Department for Transport spokeswoman backed those comment previously, saying: "Expansion at Heathrow is a critical programme which will provide a boost to the economy, increase our international links and create tens of thousands of new jobs.

"As with any major infrastructure project, we have been anticipating legal challenges and will robustly defend our position."

Under the current proposals construction could begin in 2021, with the third runway operational by 2026.