When Younghee Wait, a New Yorker and US citizen, took her family to Malta in November, they were enchanted by the Mediterranean archipelago’s beauty and culture. “My whole family fell in love with what Malta has to offer,” she says. But the visit was more than a holiday. It was a step towards buying Maltese citizenship for her family, which would allow them to live and work in any part of the EU.

Ms Wait exemplifies a new and fast-growing class of “economic citizens”. At one time, second passports were — like suitcases of cash — the preserve of spy novels. Now they are becoming increasingly common, according to the International Monetary Fund.

The fund has reported a surge in the number of economic citizenship programmes. Wealthy individuals see buying citizenship or residency rights “as a means to improving international mobility, tax planning, and family security”, the IMF said in a report last year.