The main issue is not, in fact, whether China is a security threat to the UK. That is a no-brainer. Many countries, including Britain, spy on their foes – and perhaps on some of their friends too. But the threat posed by China reflects its size, wealth and values. Delivering his annual threat update on Thursday, the head of MI5, Sir Ken McCallum, said that he encountered that threat on a daily basis. “Do Chinese state actors present a UK national security threat?” he asked. “The answer is, of course, yes.”