A crucial material in wiring and electronics, copper has long been seen as a barometer of global economic health. But in a period of low interest rates and quantitative easing, “Dr Copper can be a quack”, says one commodity trader. He may have a point.

Take the movement in the price of the red metal, which surged last week to a seven-month high of $7,460 a tonne for three-month delivery on the London Metal Exchange. Was this a sign that all is well again with the world economy, and China, in particular, which consumes about 40 per cent of global copper supply? Or was copper sending confusing signals?

Most base metals analysts, who are bearish on copper, thought the latter. Mine production during 2013 was surprisingly strong with plenty of concentrate, a basic form of copper product, hitting the market. Yet in recent months the supply of the refined metal has become extremely tight – LME stocks are at a 12-month low – pushing the copper price higher.