Is succession planning really that complicated? Plenty of recruitment specialists and management consultants will tell you it is – and extract a rich fee for doing so. But surely the search for candidates, canvassing of shareholders’ interests and prompt and decisive appointment of the chosen one are simple.

Apparently not. BP knows better than most about the risk of unforeseen events, following the tumultuous departure of Lord Browne as chief executive in 2007. The oil company and its investors now appear bent on making the arrival of a new chairman almost as messy.