De Castries said there were "flaws" in the construction of the euro which have created the cracks.

CNN: AXA boss: A Greek exit will not fix Europe

But the debate between the de Castries and van Rossum camps will roll on for several years to come.

ECONOMIST: Do mergers of banks and insurers make sense?

Mr de Castries, it turns out, does not exactly practise what he preaches.

ECONOMIST: Do mergers of banks and insurers make sense?

Mr de Castries believes that strategic alliances between banks and insurers are enough.

ECONOMIST: Do mergers of banks and insurers make sense?

De Castries, a fan of Greek mythology, believes a Greek exit would be akin to opening a Pandora's box.

CNN: AXA boss: A Greek exit will not fix Europe

The worst-case scenario, according to de Castries, would be a disorderly default by Greece leading to its collapse out of the euro.

CNN: AXA boss: A Greek exit will not fix Europe

Mr de Castries has doubts about whether this combination is so weatherproof.

ECONOMIST: Do mergers of banks and insurers make sense?

And although employees and shareholders are only speculating, almost all feel certain that the name in the letter is Henri de Castries.

ECONOMIST: The difficulty of being a dauphin

De Castries points to the Spanish banking crisis as one which must be resolved so Europe can allay concerns about the strength of its firewalls.

CNN: AXA boss: A Greek exit will not fix Europe

Britain's Standard Life is on sale, but Mr de Castries is not interested in the troubled mutual, and Generali is not interested in Britain at all.

ECONOMIST: European insurance

Embarrassing, too, in that Mr de Castries, at 46, is just the sort of modern-minded internationalist that French business schools might choose as a role model for their students.

ECONOMIST: Tax evasion