Part Whitehall farce, part Cold War throwback, this is the inside story of the Russian "honey trap" spy who never was. How did an MP's former assistant come to be wrongly accused by MI5 of being a threat to British national security? In an exclusive interview, Katia Zatuliveter tells Panorama's Peter Taylor how she became the centre of a diplomatic row over her relationship with a Liberal Democrat MP. The 26 year-old Russian graduate reacts to being cleared of the charge - made by government lawyers - that she exploited her position as Mike Hancock's assistant and mistress to pass information to Moscow. The film also interviews Mr Hancock, who sat on the Commons Defence Select Committee and chaired its all-party Russia Group, and speaks to former Russian and British intelligence officers who warn of new security tensions with Moscow.