Sergei´s case is ruled out of time, security services did not take any seriously for over a decade. Despite at least two lethal attacks on UK soil, the hybrid warfare, and the taking of Crimea. Russian troops build up at the Ukrainian border, and still..... then they attack.
https://open.spotify.com/episode/0km5PRhaIgEB6NR1GJpEza?si=d44282c0b48b4f7e