This is what the tunnel next to Clapham North tube station used to look like.

Zero Carbon Food / Flickr: 115829382@N02 / CC
And this is what it looks like now.

Zero Carbon Food / Flickr: 115829382@N02 / CC
Steven Dring and Richard Ballard have taken over the space.

Zero Carbon Food / Flickr: 115829382@N02 / CC
And now they're growing herbs in it.

Zero Carbon Food / Flickr: 115829382@N02 / CC
The site, which they've called Zero Carbon Food, requires less energy than a typical greenhouse.

Zero Carbon Food / Flickr: 115829382@N02 / CC
Plus, everything grown there is pesticide free.

Zero Carbon Food / Flickr: 115829382@N02 / CC
“After spending two years planning the business and testing in the tunnels, we launched a crowd funding campaign," said founder Steven Dring.
"Our intention is to raise the funds and expand into a commercial production. So far it’s going very well, we’ve raised just over £100,000 of our target which is £300,000 and we have some strong backing."
It's 2.5 acres in size, which is the same as a medium garden or a very large allotment.

Zero Carbon Food / Flickr: 115829382@N02 / CC
The tunnel was built as an air raid shelter during World War 2, with a view to expanding it into a full-blown railway after the war. But this never happened.
Except it's way cooler.

Zero Carbon Food / Flickr: 115829382@N02 / CC
BECAUSE IT'S UNDER THE GROUND.

Zero Carbon Food / Flickr: 115829382@N02 / CC