MI5

English Etymology en military intelligence, section five. Proper noun The domestic intelligence and counter-espionage agency of the United Kingdom, which operates in secret and whose primary function is to spy on terrorist organizations and others viewed as a threat to British national security. en Security Service<q:formally> Five 5 en 1956 w:Ian Fleming Diamonds Are Forever (novel) Diamonds Are Forever 2 ‘Why not let the Special Branch or MI5 handle it, Sir?’ asked Bond, reflecting that M seemed to be going through a bad phase of mixing in other people's business. en https://www.bbc.co.uk/news/articles/c3w4nwdwywno w:BBC News The service aggressively maintained its position until I produced evidence proving it was untrue - including a recording of one of the calls with a senior MI5 officer. How MI5 piled falsehood on falsehood in court in the case of a spy who abused women 2025-07-06 Daniel De Simone 2025-07-06 https://web.archive.org/web/20260319031322/https://www.bbc.co.uk/news/articles/c3w4nwdwywno 19 March 2026 Related terms en MI6 en MI9 See also en GCHQ en SAS en SBS en SIS Further reading en Organizations Espionage