The British government has expelled an Israeli diplomat in connection with the asasination of Al-Mahbouh. The British government claims to possess compelling evidence that Israel has misused at least one British Passport in the affair. Please read more here.
Europe in general and especially Britain has long been a hotbed for the operations of various intelligence agencies. The 2006 Litvinenko’s assassination by Russian Intelligence services comes to mind, for which several Russian Diplomats were expelled.