Most people who think themselves well informed know little or nothing about China. They – or I should say ‘we’ for I am just as ignorant – understand what the CIA and FSB are, and what they want. But what is the CPAFFC, and, if it arrives in your neighbourhood, should you worry? How about the United Front, the ‘magic weapon for strengthening the party’s ruling position,’ in the words of Xi Jinping? What does it do and why does China’s dictator praise it so?

I am back from the last place I expected to learn about the Chinese Communist Party:...