Delving into the underground world of urban farming with a WWII air raid shelter transformed into a high-tech lab (15 Pics)

The WWII shelter in Clapham consists of two large tunnels that were set to link the London Underground

That never happened and the shelter lay abandoned for 70 years until two entrepreneurs found it

Steven Dring and Richard Ballard grow an array of vegetables using hydroponic growing methods

Under an anonymous back street in south London lies a vast underground air-raid shelter that has been turned into a pioneering urban farm supplying supermarkets and restaurants in the capital

The World War II shelter in Clapham consists of two large tunnels that were intended to one day become an extension of the London Underground. That never happened and the shelter lay abandoned for 70 years until two entrepreneurs, Steven Dring and Richard Ballard, discovered it

Staff wear protective clothing and there is a strong smell of vegetables and humidity in the shelter. The vegetables are grown with hydroponics, using nutrient solutions in a water solvent instead of soil

Customers include Marks and Spencer which offers the produce in some of its supermarkets, several stalls at London's Borough Market and many restaurants - helped by the patronage of celebrity chef Michel Roux Jr. of Le Gavroche 

Micro greens seeds are processed inside buckets filled with water at the urban farm project, 'Growing Underground'

Dring and Ballard latched onto the concept of vertical farming - producing food in vertically stacked layers - which was developed by US biologist Dickson Despommier in his 2010 book The Vertical Farm: Feeding the World in the 21st Century

Dring and Ballard's request to use the air-raid shelter in Clapham was eagerly taken up by the owners of the space, London's public transport company

Experts say vertical and urban farming could be ways not only of facing up to population growth but also growing urbanisation worldwide as well as climate change. Above, a temperature, humidity and C02 monitoring device 

Nottingham University's Centre for Urban Agriculture said on its website that urban farms create jobs, reduce transport costs and pollution as well as offering an 'opportunity to develop technologies'

The Growing Underground project sends its data on humidity, temperature and plant growth to Cambridge University to try and improve efficiency

Every day is the same in the underground farm and there are no seasons, or unpredictable British weather

The micro herb broccoli takes between three and five days to grow before being packaged up in the shelter and sent off. Fans enthuse about the intensity of the flavours of the produce

The tunnels have no natural light and are illuminated with pink LEDs, giving them a futuristic look

The intensity of the light changes to imitate daylight, but with one major difference - the lights are dimmed during the day and shine brightest at night, as electricity is cheapest then