Photo: Angelika Warmuth/DPA/PA Images

Returning to Beijing recently, I carried in my head images of the city I left in January 1979, when the Reform Era was just dawning. But that city has gone. The hand of God has swept it away, and dropped in its place a gleaming megalopolis of steel and glass, whose dimensions stretch the mind to its limits. This new city speaks to me of prosperity and stability—but are China’s rulers as strong as it suggests?

SUVs choke avenues that run to the horizon, and shining office towers soar to the sky. Physically, Beijing speaks of impeccable order: streets intersect at right angles, and square-shouldered apartment blocks, hardly varying in height, march across the city like regiments on a vast parade ground. Mile after mile of roses bloom with perfect discipline down the centre of highways. Detachments of uniformed hygiene workers keep the streets free of litter, and the toilets free of germs. Your handbag is safe on your arm and no office workers throw up in the gutter after Friday evening binge-drinking.

In the city centre, Cartier, Gucci and Prada compete to cover store fronts with massive signs as nowhere else in the world. Didi has defeated upstart Uber, and produces taxis at the digital click of my finger. To hire a bicycle I unlock one with a smartphone app; at the end of my ride I can leave it anywhere. I can buy almost anything online, and take delivery of simple goods in just one hour. WeChat offers more services than any other online business in the world. Online retail sales in China in 2016 were 90% higher than in the US. The Communist Party keeps a low profile. Smart policemen stand stiff as mannequins at every subway entrance, or patrol in pairs like clockwork dolls, but the harsher forces of repression are invisible. Beijing proclaims that society is stable, economic growth will never end, and the one-party dictatorship is invincible.

So why does Xi Jinping believe that the Party is fighting for its life? Because he knows that behind this gleaming facade lies another reality. He knows that the people who live and work in the soaring buildings dare not drink tap water, their life expectancy has been cut by five years by polluted air, and cancer is growing in their babies’ lungs due to…

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