When a terrorist group is active in the UK — as Islamist extremists and dissident republicans are at the moment — there is no more essential figure in the prevention of carnage than an agent working for the security services. Reliable intelligence is what defuses bombs, intercepts arms caches, and apprehends suspects. Its acquisition can involve unimaginable personal risks, in circumstances of nerve-shredding tension. We should all be grateful, but most of us never get to know what to say thank you for, or to whom. An agent’s success manifests itself in nothing happening. Its continued value depends on secrecy.
Is MI5 grateful on our behalf?