The "sheer folly" of building a third runway at Heathrow has been highlighted by news that Gatwick could use an existing reserve runway, according to Wandsworth Council leader Ravi Govindia.

With both airports vying to provide additional capacity, and strong opposition to any further expansion at Heathrow, it has emerged that Gatwick may soon seek permission to operate a little used runway that already exists.

Gatwick has a standby runway which it uses as a back-up when its main runway is out of action. A planning condition dating back 40 years prohibits its routine use stipulating it can only be used when the main one is closed due to maintenance or emergencies.

This planning condition expires next year and there are indications that Gatwick will seek permission from the Government to begin operating it as a second runway.

It is estimated that Heathrow’s expansion plans would cost around £12 billion. It would involve the demolition of approximately 1,000 homes in the surrounding area and require the M25 motorway to be diverted through a tunnel of around three miles in length.

It would mean an additional 260,000 flights over London every year along with an estimated 25 million more vehicle movements. Heathrow already breaches air quality laws and adding this number of extra flights and vehicle journeys would create even more serious health problems for Londoners.

It would mean more noise nuisance for millions of people that live under the existing flightpaths – and expose many more people to intrusive aircraft noise for the first time. In contrast, utilising the second runway at Gatwick would have less of an environmental impact and retain noise levels within its existing footprint.

Cllr Govindia said: “This is the ultimate no-brainer. The Government wants an extra runway in the south east and here is one that’s already built that could be brought into full use at minimum cost. and at almost a moment’s notice.

“No-one in their right minds could possibly argue that it would be better to spend £12bn on yet another Heathrow runway that will take years to build, involve the destruction of many small communities, the loss of people‘s homes and businesses, huge increases in noise disturbance and incredibly harmful reductions in air quality.

“Heathrow is already the busiest airport in Europe and brings in more flights over built-up areas than any other European airport. There can be no justification for making it more intrusive when an affordable and easy alternative already exists at Gatwick.”

In response to Cllr Govindia, Back Heathrow's executive director Parmjit Dhanda: “I don't know where Councillor Govindia has been for the last three years since the Independent Airports Commission took place. This is not about Heathrow versus Gatwick, they are different types of airport that serve different purposes. Heathrow is an international hub airport, the only one in the UK and that is why it has so many businesses that trade internationally located near it. Gatwick provides a lot of holiday flights to Europe.

"As the recent NPS consultation stated, small airports like Gatwick may also need to grow sustainably, but the decision was made by a majority of nearly 300 MPs that the hub capacity will be grown at Heathrow, with a new runway. Cllr Govindia is in charge of a lot of council tax payers money, some of which he has already wasted on legal fees on this issue, so it's really important that he brushes up on the facts."