Colombia to London: the coke trail

It takes approximately two hectares of coca bushes - Ethyroxylum coca - to make one kilogram of coca paste; the exact amount will depend on the variety of coca leaves used. The leaves are crushed in a pozo, a pit or drum that allows four or five men to work the leaves into a thick, light-brown paste. The process also involves chemicals, including sulphuric acid and kerosene.

One kilo of coca paste will earn the farmer around $1,500, more than half the annual income of an average Colombian. Processed at a jungle refinery, the paste is dissolved, filtered and dried. One kilo of paste will make 800 grams of powdered cocaine.

Exported to drug-traffickers in America or Europe, and diluted by street-level dealers, one kilo of cocaine is worth £100,000-plus on the streets of London.