From svobodanews.ru [my tr.]:
London has already told Moscow on several occasions that it won’t extradite the people whom the Russian General Prosecutor’s Office believes are criminals. What might be the consequences of a possible refusal by Russia to extradite Andrei Lugovoi to Britain?
Oleg Gordievsky: There will be no consequences. The British are well aware, as are all the NATO countries, that the Russians don’t extradite their murderers, and will hide them. Of course, he’ll be blacklisted for travel abroad, but nothing will happen. Because that’s just the way it is.
Won’t it have any effect on Russian-British relations?
Oleg Gordievsky: Yes, it will. All relations will be deep frozen. I am personally going to insist that the Russian ambassador is expelled for six months, and that the main KGB operatives, namely the resident and head of Line N (i.e. the illegals), are deported. Because this operation was obviously done with the help of the illegals. And they have an employee. Those are the two people who must be deported. And the ambassador - as a demonstrative gesture