Here's how it worked. The East India Company began collecting taxes in India, and then cleverly used a portion of those revenues (about a third) to fund the purchase of Indian goods for British use. In other words, instead of paying for Indian goods out of their own pocket, British traders acquired them for free, "buying" from peasants and weavers using money that had just been taken from them.

[...] The re-export system allowed Britain to finance a flow of imports from Europe, including strategic materials like iron, tar and timber, which were essential to Britain's industrialisation. Indeed, the Industrial Revolution depended in large part on this systematic theft from India.

On top of this, the British were able to sell the stolen goods to other countries for much more than they "bought" them for in the first place, pocketing not only 100 percent of the original value of the goods but also the markup.

After the British Raj took over in 1858, colonisers added a special new twist to the tax-and-buy system. As the East India Company's monopoly broke down, Indian producers were allowed to export their goods directly to other countries. But Britain made sure that the payments for those goods nonetheless ended up in London.