Agricultural tech company Zero Carbon Farms grows plants in Clapham, south London. However, the densely populated area has no room for conventional agriculture. That is why they chose to go 100 feet down, below the ground, where there are over half a mile of tunnels.

Olivia O'Brien is the business development director at Zero Carbon Farms: "Growing Underground is the first farm for Zero Carbon Farms and what we do here is we sustainably grow fresh produce in former World War Two air raid shelters. 'We grow this both for the fresh produce industry and also the extraction market. And the way that we do it is we use renewable energy, we use recirculating water, and we're able to grow the crops 365 days a year with little impact on the environment.''

Zero Carbon Farms says farming here uses 70-90% less water and 95% less fertilizer than typical agriculture. Their fresh produce can appear on a diner's plate within two hours of harvest - producing minimal emissions on the journey to get there.

"Their yields and the efficiencies of their growing times are as optimized as possible. That also means that you get incredibly nutritious, very, very tasty crops that you know will have a very long shelf life. So you get less food waste because of things like that.''

Zero Carbon Farms plans to double its growing space in 2023.