Wulf Bernotat is a stickler for rules. A lawyer by training, the chief executive of Eon – the world’s largest utility by sales – arrives at this interview in an open-necked shirt, in accordance with Casual Friday at the company’s west German headquarters. His press officer looks for a tie for the photographs but the jovial 59-year-old manager is not about to change. “Let’s get on with it,” he says.

His desire to abide by the rules has, on the surface of it, been costly this year. The German electricity and gas group suffered the humiliating defeat of its two-year fight to take over Endesa in Spain as an alliance of Enel and Acciona audaciously snatched victory. The Italian and Spanish groups made a series of bold moves that blindsided Eon’s by-the-book strategy.