K, you say, "In the days of the cold war, any information was in a way secret."
No, it WASN'T! Telling someone in Castro's Cuba that the London station he would need to go to if he wanted to get to Edinburgh most easily was King's Cross wasn't secret. Nor was the result of the Arsenal v Chelsea game on May 18th 1985 something to be kept under wraps, was it? (I've no idea whether there was such a game on that date, but you get the idea, I'm sure!)
The current Czech spy absurdity is all about the supposed sale by Mr Corbyn of "BRITISH SECRETS" , which automatically implies 'Government' ones, such as nuclear deals, sales of military equipment, Prime Ministerial visits and so forth, as you well know.
Not a shred of evidence from the Tory press, nor from you, nor from any of your apparent supporters in this thread or elsewhere has been presented that Corbyn did any such thing during the Cold War nor at any other time!
Instead, you and they keep on insisting that it is up to Corbyn to prove that. NO IT ISN'T! That's not how the British system works. If someone is accused of doing something illegal or treasonous, it is 100% up to the accuser to prove that...the accused does not have to lift a finger to prove he is innocent!
So, there you go; show me what the evidence is for the claim that Mr Corbyn sold secrets to a Czech spy without wasting time on telling me about utterly irrelevant activities he may have indulged in elsewhere.