The doubling of the spot copper price since January to more than $6,000 a tonne has taken the headlines in the base metal market. But it is the price movements in copper far forward contracts that have been even more dramatic.

The London Metal Exchange 63-month copper price – a traditional forward contract benchmark – jumped earlier this month to $5,861 a tonne, approaching its all-time high of $6,998 a tonne set in May 2008, and its highest level for almost a year.