The trail led to the United Kingdom, the biggest consumer of heroin inside the European Union.

Expenses soared. Wealth was being made that the humble, illiterate farmer in Afghanistan could not comprehend – but the men bringing the trail to its end had made evaluations of risk against profit. The risk was a prison sentence of twenty-five years in a maximum-security gaol, but the profit was huge.

Only a few had the skill to stay ahead of the ever more sophisticated techniques of law enforcement set against them. By ferry, tunnel, car or coach in the bags of pensioner tourists who saw no wrong in making easy money, inside the cargoes of lorries, and by boat to unsuspected landing points where vigilance had slipped, the freight landed.

A man had paid up and housed what he had bought in a warehouse or a lock-up garage. He was a baron and remote from the process of the street. He sold split portions of what he had purchased to a network of regular suppliers; he was hands-off, crucial to the process but distancing himself as far as he could from risk, while retaining as much as he could of the profit.

The supplier further diluted the purity of the heroin with flour, chalk or washing powder, made more divisions and traded with dealers, the street gangs who controlled a small area of territory in a country town, a provincial city or in the capital. The supplier took his share.

The dealers sold on the street, but only after further dilution. They were the last in line and their cash rewards were as meagre as those of the mountain farmers. The dealers had the addicts begging them for wraps – tonnage reduced down to a single gram, enough for a day's hit. No cash, no sale. Without money the addict was shut out as a customer.