Britain's Gini coefficient is substantially distorted because of London. The Gini coefficient is a pure measure of income inequality, so is massively influenced by the presence of people with exceptionally high incomes. It tells you almost nothing about the gap between the middle class and the working class in a developed country. When your country includes a megalopolis that's the world's most popular playground for billionaires and tax haven for multinationals, that distorts the figures somewhat. Factor out a couple of London boroughs and our Gini index changes dramatically. Likewise, France's Gini index would plummet if they had a territorial claim to Monaco.