Michel Pébereau, the mercurial head of BNP Paribas, will be painfully aware of the dangers of running ahead too quickly at the beginning of a long race.

After his blitzkrieg attack on Crédit Lyonnais, in which he swiped more than 16% of the company from under the noses of Crédit Agricole, Pébereau has stormed into an early lead to win control of the former ugly sister of French banking.