The oil and gas companies bestride the world, the biggest and most profitable companies on the planet acting as a law unto themselves as their products fuel the global economy. This is a common perception of the sector but the energy companies do not have it all their own way.

In the 1960s, the oil majors had access to 85 per cent of the world’s oil reserves – now they have access to only 16 per cent as governments assert control over their national assets. The contrast between the list of the world’s biggest oil companies by revenue and by access to reserves (barrels of oil equivalent) is striking. Exxon-Mobil may be the biggest and most profitable company but it ranks only 16th in terms of reserves, well below the likes of Gazprom, Lukoil and Petrochina, according to Petrostrategies, the consultancy.