When any spy dies that’s just part of the game. When a double agent dies then he/she double-crossed two clients at the same time. Under no condition does a country in which the spy dies, retaliate against the spy’s homeland.
The present situ in Britain where a Russian double-agent was poisoned along with his daughter does not call for the massive over-reaction that has occurred. There is no reason for Prime Minister Teresa May to throw out official Russian representatives in retaliation for some corrupt individual’s death.