Quote Originally Posted by ian 2411 View Post
Before anyone mentions it I would just like to say we have most likely got a few cells in the UK, and as in all cases of spy’s getting caught, we will probably find a few as well.
Don't forget about OUR spies, all around the world. If we don't have at least as many agents poking around in Russia as they have here, the CIA, NSA and all the other alphabet soups aren't doing their jobs.

As for waiting ten years, sometimes its a case of the Devil you know being better than the Devil you don't. If you know someone's a spy, and they don't know that you know, you can feed them bad intel. If you arrest them, there will be a new agent in place within days, if not sooner, and you won't know who it is.