If your first reaction was "the City", think again. The answer is North Sea oil. One of the peculiarities of British politics – and economics – is the reluctance to take into account the critical contribution of oil to the economy. We spend so much time droning on about our excessive reliance on the financial sector that we tend to ignore this elephant in the room. But the truth is that, for the past quarter of a century, Britain has been a petro-economy. In 1999, we were producing more oil than Iraq, Kuwait or Nigeria. The following year, we pumped out almost twice as much natural gas as Iran – a country with reserves that are the envy of the world.