Ol' Mitt is one of many who have vast amounts of wealth offshore.
Oil-rich states with an internationally mobile elite have been especially prone to watching their wealth disappear into offshore bank accounts instead of being invested at home, the research suggests. Once the returns on investing the hidden assets is included, almost £500bn has left Russia since the early 1990s when its economy was opened up. Saudi Arabia has seen £197bn flood out since the mid-1970s, and Nigeria £196bn.
"The problem here is that the assets of these countries are held by a small number of wealthy individuals while the debts are shouldered by the ordinary people of these countries through their governments," the report says.
The sheer size of the cash pile sitting out of reach of tax authorities is so great that it suggests standard measures of inequality radically underestimate the true gap between rich and poor. According to Henry's calculations, £6.3tn of assets is owned by only 92,000 people, or 0.001% of the world's population – a tiny class of the mega-rich who have more in common with each other than those at the bottom of the income scale in their own societies.
Time to change some policies. Obviously the filthy rich don't need all this money to live on.