The two men were shot by two men wearing Afghan police uniforms.
The inquest heard an intelligence report that said "insider threat" was difficult to detect. Insurgents and the Taliban used this kind of attack as a tactic and there had been no increase in this kind of threat.
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James Watson who was arrested over the unsolved 1994 murder of schoolboy Rikki Neave claims to be in Portugal having skipped bail.
People have been wandering into the grounds trying to catch the cartoon monsters.