With the death of Prince Rainier, Europe has lost its longest-serving monarch, and Monaco a ruler whose charm and wiles allowed a principality of only 482 acres to survive and flourish. His achievement in transforming what Somerset Maugham called “a sunny place for shady people” into a state with international recognition and a seat in the United Nations is considerable. In 1949 gambling accounted for 95 per cent of Monaco’s income; now the famous casino provides less than 3 per cent of annual revenue.

Changing a lazy laissez-faire lifestyle and securing Monaco against external threats and corruption from within has not been easy. Like most small states, Monaco has grown rich by being a tax haven. This almost led to invasion in 1962, when an infuriated de Gaulle stationed troops on the border to force French residents to pay French taxes. Today the European Union and international organisations are equally irritated by Monaco’s dependence on its loophole status, and are urging greater financial transparency. This, and accusations of money-laundering by Russian businesses seeking to hide their money, is a challenge for Prince Albert.

Around the world territories too small to qualify as normal nation-states are seeking niche markets as financial centres and tax havens. But this is a precarious policy. Monaco has instead diversified in marine biology, upmarket tourism and conferences. Much of this was thanks to the personal interest of Prince Rainier, who in his beneficent if autocratic 55-year rule showed a shrewd grasp of Monaco’s needs. Stability and prosperity are a solid legacy for Prince Albert.