The Liberal Democrats could be poised to help "change the direction" of the country if they successfully pull off a spectacular by-election victory in Zac Goldsmith's constituency, Tim Farron has said.
Environmentalist Mr Goldsmith announced on Tuesday that he would quit as Tory MP for Richmond Park following the government's decision to nominate Heathrow as its preferred choice for airport expansion.
Speaking to ITV News, the Lib Dem leader said: "Given this is the constituency most hit and worst hit by the extreme version of Brexit Theresa May has chosen to adopt, this is an opportunity for them to send a message to this government that could change this government's direction."
ITV News Deputy Political Editor Chris Ship said: "This by-election is in an area where 70 per cent of people voted to remain in the EU. The Lib Dems position themselves as the most pro-EU party, so they are hoping for something good from this."
Theresa May has insisted a third runway at Heathrow Airport will meet the required air quality standards.
Responding to concerns raised at Prime Minister's Questions by Tania Matthias, the Tory MP for Twickenham, Mrs May said: "The government looked very closely at this issue of air quality and environmental impact of all three schemes that were proposed by the Airports Commission. We took extra time to look at those. We wanted to look more particularly at the air quality issues.
"The evidence shows that air quality standards can be met as required by all three of the schemes including the north west runway at Heathrow.
"But... the issue is about more than airports, because the question of air quality is also about road transport and that's why we are looking to do more in relation to what we're doing for air quality. It's why, for example I'm pleased to see that we're at such a leading edge in the provision of electric vehicles."
A new runway at Heathrow Airport might be built over the M25, the Transport Secretary has said.
Chris Grayling's comments follow Tuesday's announcement that the government has chosen Heathrow as its preferred airport expansion project.
Speaking on BBC Radio 4's Today programme, Mr Grayling said: "One of the things that Heathrow has been looking at is doing what many other airports have done around the world - which is to build their runway over the top of the road rather than tunnelling the road underneath it.
"It is a cheaper and quicker way of doing it. I am, of course, very concerned to make sure that, as this runway is built, it doesn't cause massive disruption on the M25, so I think this is a sensible way.
"It is a very gentle hill up which the planes would take off rather than a flat surface. It's what happens at very many airports around the world."
A government decision to build a third runway at Heathrow means the airport will only get much busier.
While the controversial decision might mean economic lift-off for Britain, it spells a period of turbulence for Theresa May as Prime Minister.
ITV News Political Editor Robert Peston reports:
Lives and livelihoods could be affected in different ways across the country by the Heathrow Airport expansion, ITV News Consumer Editor Chris Choi reports.
Nearly 800 homes are threatened by demolition and much of the village of Harmondsworth could end up under the tarmac of the third runway.
Resident Eilish Stone said: "I find it absolutely insulting that people think they can come in bulldoze our home, bulldoze our villages and we are just happy to take the money and run."
But it is also claimed the new runway will boost the UK economy by £211 billion and create 77,000 jobs.
- Video report by ITV News Deputy Political Editor Chris Ship
Ministers chose the Heathrow Airport expansion over Gatwick to show, post-Brexit that the UK is "open for business", according to Transport Secretary Chris Grayling.
The expansion will be paid for by private companies at an estimated £17.6billion, but it is politically risky with critics within the cabinet including Foreign Secretary Boris Johnson describing it as "undeliverable".
And the resignation of Zac Goldsmith, triggering a by-election in his Richmond Park constituency has already proven the decision to be politically fragile.
The Conservatives have announced they will not fight the by-election triggered by former MP Zac Goldsmith, who quit in protest over the Heathrow expansion.
A statement by the party said they "disagree" with Goldsmith but "understand his position".
The statement added: "He has been a hard-working champion for the people of Richmond Park - as we know he will continue to be if they re-elect him as their Member of Parliament - so we will not be putting up a candidate against him at this by-election."
Environmentalist Goldsmith called the move "catastrophic" - and announced he will now stand as an independent in protest.Read the full story ›
Heathrow Airport has thanked Amsterdam's Schiphol Airport "for letting us borrow your runway" after the Government confirmed plans for a third runway at the London hub.
Schiphol is connected to 24 airports across Britain, making it the leading flight hub for UK travel.
Heathrow exchanged light-hearted cake-based tweets with the Schiphol account, saying it wouldn't "need (the Dutch runways) much longer".
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