The Corporation exists outside many of the laws and democratic controls which govern the rest of the United Kingdom. The City of London is the only part of Britain over which parliament has no authority.
The City has exploited this remarkable position to establish itself as a kind of offshore state, a secrecy jurisdiction which controls the network of tax havens housed in the UK's crown dependencies and overseas territories. This autonomous state within our borders is in a position to launder the ill-gotten cash of oligarchs, kleptocrats, gangsters and drug barons.
It has also made the effective regulation of global finance almost impossible. Shaxson shows how the absence of proper regulation in London allowed American banks to evade the rules set by their own government. AIG's wild trading might have taken place in the US, but the unit responsible was regulated in the City. Lehman Brothers couldn't get legal approval for its off-balance sheet transactions in Wall Street, so it used a London law firm instead.
If you've ever dithered over the question of whether the UK needs a written constitution, dither no longer. Imagine the clauses required to preserve the status of the Corporation. "The City of London will remain outside the authority of parliament. Domestic and foreign banks will be permitted to vote as if they were human beings, and their votes will outnumber those cast by real people. Its elected officials will be chosen from people deemed acceptable by a group of medieval guilds …".