Poker has long had an informal investment economy where players stake others or are staked by wealthy friends.

WSJ: $1 Million Ante Lures Poker Investors

Meanwhile, remittances from abroad, self-employment, tourism, foreign investment and the informal economy have lifted the incomes of a large group of Cubans.

ECONOMIST: Cuba's economy

They rely on retained earnings and foreign direct investment, or else on informal sources of credit.

ECONOMIST: Casino capital

The fourth kind of empire, suggests Mr Darwin, was a more informal one in places such as Argentina and Egypt where British influence was exercised through commerce, investment and shrewd diplomacy (occasionally of the gunboat kind).

ECONOMIST: The British empire: Pondering the past | The