Prices for the metal hit a record high after the president suggested a higher rate than many analysts were expecting.

While the cost of copper is going up for American businesses and consumers, the rest of the world is scratching its head while it enjoys a considerable discount on the price of copper.

Donald Trump's mooted 50% tariff on copper imports into America has sharply exacerbated what was already a dislocation between New York and London prices for the metal. The chart shows that since Trump's inauguration traders have been placing a greater premium on the COMEX contract,