Who is really in charge of companies? The question is provoked by reading the green paper on corporate governance at financial institutions, published this month by Michel Barnier, the European Union’s Internal Market Commissioner.

Barnier has asked whether shareholders are exercising all their power. This is a reasonable question. There is some truth in the saying, "who holds the purse strings holds the power". According to that mantra, shareholders ought to have the final say on the big questions facing companies.