The situation is exacerbated as the average tax paid by ultra high net worth individuals remains very low when their incomes are taken into account, while they have access to multiple ways to reduce their tax bills.

The EU Tax Observatory is calling for a global minimum tax on billionaires, equivalent to 2% of their wealth. ‘We provide a first estimation of the revenue potential of this measure, showing that it would raise close to $214bn (£176bn) from 2,756 individuals annually, who have total wealth of $13 trillion,’ the group said. This would be equivalent to around an additional tax charge of $7m per billionaire a year.

It is also calling for a mechanism to tax wealthy people who have been long-term residents in a country and choose to move to a low-tax country. Another measure it criticised was the use of non-dom status which is used widely in Europe and of course the UK to offer preferential taxation of worldwide income. Schemes currently operate in the UK, Greece, France, Ireland, Italy, Luxemourgh, Malta, Portugal, Spain and Switzerland.