When Jamie Dimon hears the word “culture”, he reaches for his chequebook. The rich price at which JPMorgan Chase reportedly plans to exercise its option to buy out Cazenove from the two companies’ joint venture is in part a bill for the aura that the venerable City stockbroker has managed to maintain.

It’s a compliment – think of the lowball price that Mr Dimon first offered for Bear Stearns – but how can the JPMorgan boss now ensure that guardians of the Cazenove culture who stand to gain from the deal stick around?