This figure, reported in the Daily Telegraph on February 26 and then picked up by other newspapers, was analysed by Dr Ben Goldacre on his Bad Science blog as follows:
"We could be generous and say that heroin is worth $2,000 per kg in Afghanistan. So fine: this would make the army's (potential) 130kg of heroin worth about $250,000.
"'That's still not 50m [pounds sterling]. Where did this number come from? Perhaps everyone was trying to calculate it by using the wholesale price in the UK, assuming that the Taleban ran the entire operation from 'farm gate' to 'warehouse in Essex'. This is a stretch of our generosity, but we can give it a go: the wholesale price of heroin in the UK has fallen dramatically over the past two decades, from $54,000 per kg in 1990 to $28,000 in 2006. That would make our 130kg of (potential) heroin worth $3.6m.
"We're still nowhere near 50m [pounds...