Since the imposition last week by US president Donald Trump of tariffs on US imports from nearly all its main trading partners – ranging from 10 per cent to 50 per cent – the most tangible impact has been a sharp fall in global stock markets. At the time of writing the US market was down 10 per cent since last Wednesday, the UK was 7 per cent lower, and China’s stock market was down 12 per cent. Who knows where they will be by the time you read this? Stock markets are a proxy for many things but fundamentally...