Spring appears to have sprung in the base metals sector as a powerful rally has lifted prices for copper, lead, nickel and tin sharply higher, leaving investors who had bet that weaker economic growth would push prices lower shouldering big losses.

The strength of the rally – copper is more than 40 per cent more expensive now than at the beginning of the year, for example – has not only caught some traders by surprise; the mining industry is also astonished because it comes in the face of collapsing industrial output and construction activity worldwide.