Shareholder failure to police risky management activities was largely due to the very short holding periods for equities. A suitably high transaction tax would force investors to hold shares for much longer periods and to engage management to control risk. This would reduce the need for governments to police risk-taking in corporations.

Wrong!  Shareholder failure to police risky management activities is a design feature of current corporate governance. It is hardly surprising that the author of an editorial in the FT is oblivious to this basic fact.

I will give the author credit for the observation that changed economic circumstances will potentially pit those with responsibility for governing against those with responsibility for managing other people's money, or at least give the appearance of so doing.  However, the functional capture of governments in the USA and the UK by the financial sectors will inhibit efforts to protect what those in government see as the national interest.

Any move to control capital flows would have to be prepared under conditions of secrecy that are unlikely to hold, given the current directions of loyalty and patronage, and at the first hint of such action the government would be reeling from dealing with massive capital flight. Perhaps international coordination that left capital only such destinations as Burma or the Central African Republic would help, but what is to be done with capital that is already out of the country?  

My guess would be that an international crisis where a nuclear exchange is in the offing, especially were old superpower rivalries bruited to be involved, would be the best way to get the money home. Else, Iranian terrorists threaten to detonate a weapon in the harbor at Monaco, Cuba sends troops to Grand Turk, narcotraficantes threaten coup in Panama, US military paralyzed, etc.  What can I say?  Laughs are hard to come by these days.

"It is not necessary to have hope in order to persevere."