What did BIS know and when did it know it?

If a Russian intelligence service wanted to deliver ricin poison to the embassy in Prague for assassinating local Czech politicians, only a handful of people would know about it. That's not something you write in a memo. If one of those with a need to know then wanted to pass on the information to the BIS counterintelligence agency, the person would need to choose the language of communication and the means of delivery so that the leak couldn't be traced back to him or her. That's not easy when you're going rogue and aren't able to rely on your own service for running interference. The key moment in the "fake ricin" matter came when BIS decided, despite these obstacles, that the communication it received from an anonymous source amounted to credible threat intelligence. The nagging question, given BIS's history of self-promotion, is whether its initial assessment of a credible threat was professionally based or part of a political game that came back to bite it later.