When Citigroup's Sandy Weill – allegedly – telephoned German Chancellor Gerhard Schröder to discuss a possible takeover of Deutsche Bank, little did he know his actions could have helped trigger a boom in European mergers and acquisitions. This is what his hordes of deal-hungry investment bankers have been dreaming of for months.

By all accounts the conversation was friendly – as would have been the planned merger – and the subject of a job for Schröder was discussed. But months later, thanks to a combination of politics, protectionism and boardroom aggro, the hotline went dead.