Historian Paul Johnson devotes his latest Forbes magazine column to an interesting economic fact regarding London.

A remarkable fact of international life today is the emergence of London as one of the foremost capitals of the superrich. It ranks fourth in the world with 45 billionaires. (Moscow is first with 88, but it seems there’s nary a one of them who doesn’t have a home in London–which tells you all you need to know.)

A chief reason London attracts the very rich is security. Nobody’s going to be arrested, executed, imprisoned or have his or her fortune confiscated simply because of pique.

Another factor is the successful stewardship of Boris Johnson, who has twice been elected London’s mayor. Boris, as he is universally known, exudes a mixture of glorious optimism, business savvy and sheer charm. As long as Boris is in charge, billionaires living in London can be sure that no legislation–national, regional or local–will be allowed to mitigate against the making of money. …

… The fact is, London is the best center in which to do business of the highest class. Every conceivable financial outfit, literally, is within call–usually within a five-minute walk. To set up a multibillion-dollar deal costs noticeably less in London, takes far less time and, if sensibly managed, is far more likely to succeed than in any other financial center.

London also has a marvelously flexible, comprehensive and (pretty much) honest legal system, which explains why the superrich often prefer to litigate in London, even if they don’t actually live there. …

… Looked at from a global perspective, London’s position appears to be secure, provided it maintains its prudent attitude toward wealth. Its largest rival is Moscow, with its special–and highly precarious–treatment of Russian oligarchs. Paris now has only 21 billionaires–and is fast losing those, thanks to François Hollande’s 75% tax regime. Mumbai, which, given the general wealth of India, ought to have scores of billionaires, also has 21. Beijing, with its fierce restrictions on capital movement, preventing its highly successful exporters from expatriating their profits, has 36, and Taipei, whose economy is about 5% of mainland China’s, has 20.