I've been hunting for old science fiction books and TV shows from my childhood. This question is about a TV show (or it may have been a film) shown on the BBC in the late 70's or early 80's.
In my memory it is science fiction but it could as easily be a spy thriller (although my passion has always been SF, so I find it unlikely to have been a spy thriller unless it was set in the future).
I recall one scene vividly. A man walks into a large round room, reminiscent of a telescope observatory dome. On a pedestal in the middle of the room is a huge gun, like you would find on the deck of a battle ship. It is very cold in the room and the man's breath is misting.
I recall a title "Cold City" but don't know if that refers to this show or if it is simply incorrect. I also recall the idea that the man was sent to sabotage the gun, but I could be confusing two different stories.
It was live action. It may have been dubbed but I find this unlikely.
Very obscure and hazy memories! Hope some one on this site might remember it?