On 11 June 2015, a white-haired old man stood in the dock of a criminal court in northern China, flanked by officers who had once answered to his command.

For years he’d been the most feared man in China, controlling police, paramilitaries, prisons and intelligence operations. But in the year-and-a-half between vanishing from public life and reappearing in court, this 72-year-old had lost his jet black hair and become stooped and haggard.

Now he was the target of the Orwellian security system he himself had built. And he knew better than to resist.

“I accept the sentence. I will not appeal. I realise the crimes I’ve committed and what I’ve cost the Party.”

When Xi Jinping came to power, he had promised the public a campaign which would “brandish the sword against corruption”, caging tigers as well as trapping flies.

Here was one of the biggest tigers of all. Zhou Yongkang was the most senior Party official ever to stand trial for corruption in the history of communist China.

A commentary on state TV news proclaimed: “No-one is above the law. This case shows that our country is practising the rule of law and our Party is determined to eradicate corruption.”

The downfall of another tiger – Bo Xilai – is now notorious. He and Zhou were accused of plotting together and, with two top military figures and another senior politician, of “wrecking Party unity”.

Zhou’s trial came halfway through Xi’s first term. The campaign of shock and awe was well under way with a barrage of high-profile trials and a drumbeat of righteous propaganda.

To supplement the image of a newly disciplined and frugal political culture, Xi tried to avoid banquets and sometimes travelled in a van with colleagues instead of a fleet of limousines.