The farm underneath the streets of London

In a Second World War air-raid shelter deep under the streets of London, two entrepreneurs are hoping to change perceptions that fresh produce can only be produced on farms in the countryside.

The sophisticated subterranean set-up is used to grow herbs, salads and 'micro-greens', many of which end up in some of London's finest restaurants.

Run by Richard Ballard and Steven Dring, the underground farm has been so successful with local businesses that supply has outstripped demand.

The former aid-raid shelter which houses the farm was used by thousands of Londoners at the beginning of the 1940s, but fell into disuse in the years after. It was repurposed by Ballard and Dring with the help of a crowdsourcing campaign.

Find out how the produce is grown in the video above.