States only believe in their own interests and the narrative always go towards the powerful and the one which won.

That’s the fatal flaw in international "justice" and has been from the start. Where were the people who allowed the nuclear bombing of civilians during the Nuremberg trials? Why was nothing said about the western nation entering the war so late despite what they knew? Because that’s not justice, merely retribution.

Then, you have to considered the role played by secret institutions in democratic countries. Do they serve the citizenship, the national interests (what does that even mean?), the people in power, themselves first and foremost? From history, I wouldn’t trust them very much, even less as a foreigner.

Be wary of any institution or person holding power. Check and balance are deeply needed and we should be horrified every times they are being limited or abused.

If the UK is still serious about being a liberal democracy, this should have sever consequences. I’m sadly fairly sure it won’t.

MI5/6 are never good guys.

Because people like that are useful to get inside organisations full of other evil people and prevent those organisations doing even worse things.

I hate it, but that is the logic.

The continued loyalty of their other employees, a significant proportion of whom also enjoy using their MI5 role as a tool of coercion?

All of these things together make it so that the immediate reaction to any apparent wrongdoing is to close ranks, tell nothing to outsiders like the police or prosecutors until some boss decides otherwise. And that boss will of course weigh any such decision against the risk that any minute secret might be revealed in an investigation, that any agent might lose a tiny bit of confidence, etc - and likely will brush it off and apply some paltry administrative penalty then move on.

By keeping him out of jail, Mi5 stood to gain more intelligence

Something like someone who did know him as his secret identity would see his face, hear his association with MI5 and go “Wow Dude! Turns out ‘Niegel from Birmingham’ wasn’t really ‘Niegel’ at all! Didn’t he introduce us to Tommy as his old childhood friend? Maybe we shouldn’t trust Tommy anymore either. In fact why don’t we dangle Tommy from his ankles until he confesses?” So revealing that this miscreant is MI5 could put the life of other agents in danger too.

Or alternatively it can be about protecting some method. Like this terrible person introduced a bunch of criminals to a “secure chat” application, and you don’t want them to think it is not as secure as they think. (Obviously the names and particulars are wild guesses with no basis in reality.)

Not saying it is a great argument, but that is how these kind of agencies think sometimes.

Perhaps some smaller countries have had secret services with an apparently clean record (would be hard to know for sure) at some point. But that could be more a matter of luck with who was in charge and hired at that point.

The BBC is not only a domestic tool, but a global tool for controlling the image of the British state and perceived lack of corruption.

When people start to question their behaviour, up pops this kinda counter. The judges are part of the same system.