New figures released on Monday expose the scale of illegal cannabis farming in the British capital, where police said they had found 314 farms since 2016 — the equivalent of one every two days — according to Scotland Yard data obtained by the London Evening Standard.

One policeman, Detective Superintendent Lee Hill, told the Standard that there was a "human, emotional" toll in finding cannabis farms because there are so often children being exploited on them in dangerous situations. In particular, he said Vietnamese boys and teenagers are often asked to watch over properties in case rival gangs approach or a police raid is planned. "I've recovered children who are being exploited. They are there to protect the properties," Hill said.