By Chris Dorrell Londoners have been slower to return to the office after the pandemic than workers in many large cities around the world. This really matters, and not just for London. Almost all of the UK’s economic problems can be traced back to sluggish productivity growth. Productivity, which measures output per hour, is the engine of economic growth. As Paul Krugman once said: “Productivity isn’t everything, but, in the long run, it is almost everything.” London has witnessed a sharp slowdown in productivity since the financial crisis, trailing international competitors and even falling b…