The execution of Kim Jong-un’s uncle, Jang Song-thaek, has startled the world. But how will it look to the North Korean people, and how will they react?

A source in the country has spoken of tension and whispered conversations, as ordinary North Koreans try to make sense of tumultuous events. Jang Song-thaek’s sudden fall will worry them. If even he, one of the most powerful people in the country, can be executed, so can anyone. Kim Jong-un has made it clear that utter loyalty to him is now a prerequisite for survival – both political and physical – in North Korea.

Even small, perhaps innocent, acts of deviation will be brutally punished – one of Jang’s crimes was not to stand up fast enough, or to clap with sufficient enthusiasm, when Mr Kim was anointed leader. What other misdemeanours are now punishable by death? Many of my North Korean friends used to cope with the tedium of their regular political lessons by going off into a dream world and not listening to what was being said. But I suspect that, from now on, everyone will be paying close attention in political classes, to learn what is required of them.

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The unpleasant consequences of stepping out of line will have been particularly clear to those who will have pored over the newspaper photograph of Jang at his tribunal. They may have noticed, as have photographic analysts outside the country, that Jang’s cheek appears to be bruised and that there is discolouration around his wrists.

They will also have been startled by the revelations in the official reports both of Jang’s eviction from the party and of his tribunal. Usually the regime claims that the party is united around the views of Kim Jong-un, but these reports make clear that Jang and others disagreed with Mr Kim and allegedly even plotted against him.

This will be the first time that many North Koreans have learnt officially of heresy at the top of their regime. Moreover, they are brought up to believe that Kim Il-sung and Kim Jong-il were infallible geniuses. But these reports show that both men gave their trust to a man who was “no better than a dog”. So even the demigods who have ruled North Korea can commit errors of judgement?

Few will have seen a report of a show trial before. The last one was in 1958, when Kim Il-sung dealt with an attempt to unseat him from the leadership of the party. Although both he and Kim Jong-il dealt ruthlessly with those who opposed them, neither bothered with show trials – victims were simply executed with no pretence of legal process. The wonder and bewilderment on the faces of North Koreans photographed looking at the newspaper reports speaks volumes.

North Koreans in the military will be particularly nervous. One of Jang’s alleged crimes was to plot a coup against Kim Jong-un, involving the military old guard – those senior officers appointed not by Mr Kim, but by his father and grandfather. I suspect that the complicity of such officers in the “plot” will now be investigated, and that some at least will be dismissed (usefully allowing Mr Kim to replace earlier appointees with his own men) or worse. I doubt that Jang will be the last person to die in this purge.

John Everard was the British ambassador to North Korea from 2006 to 2008