'Russian spy ring' lived at flat one mile from RAF base
By martin EVANS, Gordon Rayner & Max Stephens
Spies like us: How does Russia's intel network operate across Europe?
By David Mac Dougall
Suspected spies for Russia held in major UK security investigation
By Daniel De Simone & Jeremy Britton
Three Bulgarians suspected of spying for Russia charged in UK
By Luke Harding & Matthew Weaver