If the phrase ‘stranded asset’ hasn’t yet entered your vocabulary, here’s a useful example of what it means. The 178 million barrels of oil in the Cambo field west of Shetland may stay there for ever because of government shilly-shallying over whether and when to end exploitation of the UK’s remaining hydrocarbon resources — while we import equivalent volumes of oil or gas from the Middle East, Norway and Vladimir Putin’s Russia, just to keep our lights on.