# What does M.I.5 mean? **URL:** \ **Category:** Factual Questions\ **Created:** [August 24, 2005, 11:42pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509 "2005-08-24T23:42:39Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![bubastis](https://avatars.discourse-cdn.com/v4/letter/b/d07c76/32.png) [@bubastis](https://boards.straightdope.com/u/bubastis)\ **Post date:** [August 24, 2005, 11:42pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/1 "2005-08-24T23:42:39Z")
M.I.5 is british intellegence, right? Is it _Military Intellegence_? In which case, what does the 5 stand for? ---
**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\ **Post date:** [August 24, 2005, 11:49pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/2 "2005-08-24T23:49:29Z")
MI5 is the domestic secret service, MI6 overseas espionage. There used to be a lot of different ones, which either became obsolete or were amalgamated into the two remainind ones. [Wikipedia](http://en.wikipedia.org/wiki/MI5) gives a few examples…finding them all via Google is a task that defeated me last time I tried it. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [August 24, 2005, 11:49pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/3 "2005-08-24T23:49:39Z")
Yes, it stands for millitary intelligence, and 5 was just a bureau number. Apparently all MI bureaus but MI-5 (internal security) and MI-6 (global security aka espionage) have been discontinued. ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [August 25, 2005, 9:26am UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/4 "2005-08-25T09:26:46Z")
Alan Stripp’s _Codebreaker in the Far East_ (OUP, 1989, 1995, p148) gives a “rough guide to the wartime War Office departments” as part of a glossary of technical terms. Stapp admits that the list is actually of little relevance to his book, but includes it because “the information appears so rarely”. Simplified to avoid most of the qualifications about alterations to it during the war, the list is: MI 1 Admin MI 2 Middle East, India, USSR, Northern and Eastern Europe, Scandinavia and the USA. MI 3 Western Europe (initially including Germany) MI 4 Maps, then operations MI 5 Operations in Britain, mostly counter-espionage MI 6 British intelligence-gathering and counter-espionage abroad MI 7 Press and propaganda MI 8 Signals intelligence MI 9 Enemy and Allied POWs; escape and evasion MI 10 Technical intelligence MI 11 Military security MI 12 Post and telegraph security MI 13 Not used because it might be seen as unlucky MI 14 Germany (from May 1940) MI 15 Aerial photo reconnaissance MI 16 Scientific intellegence MI 17 Co-ordination of intelligence MI 18 Unknown MI 19 From 1941, enemy POWs MI L Liason with Allied military attaches MI L® Liason with USSR MI R Special forces, until formation of SOE MI X Recruitment Because the responsibilities shifted as stuff was divided and rearranged, many other authors writing about British intelligence in WWII commonly get confused about the more minor departments, which is always worth bearing in mind when seeing a reference to them. (MI12 in the list of examples in Wikipedia seems to be a trivial slip-up.) ---
**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\ **Post date:** [August 25, 2005, 10:08am UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/5 "2005-08-25T10:08:13Z")
Answers on [this page](http://www.guardian.co.uk/notesandqueries/query/0,5753,-20949,00.html) contradict some of those (including the absence of MI13) - although any differences are probably explained by changes to the structure over time. ---
**Author:** ![rayh](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@rayh](https://boards.straightdope.com/u/rayh)\ **Post date:** [August 25, 2005, 10:32am UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/6 "2005-08-25T10:32:21Z")
MI5/6 are no longer _Military_ intelligence services. Although the military do have some intelligence services of their own, most of these things are handled by MI5/6. Officially they are know as the Security Services, but the are quite happy to be known as MI5/6 considering the abbreviation that would be used (ie **S** ecurity **S** ervice). MI5 even has it’s own web site [her.](http://www.mi5.gov.uk/) ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 25, 2005, 2:07pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/7 "2005-08-25T14:07:27Z")
Business. 😃 ---
**Author:** ![Bippy\_the\_Beardless](https://avatars.discourse-cdn.com/v4/letter/b/ac8455/32.png) [@Bippy\_the\_Beardless](https://boards.straightdope.com/u/Bippy_the_Beardless)\ **Post date:** [August 25, 2005, 3:20pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/8 "2005-08-25T15:20:57Z")
> [@rayh](#): > > MI5/6 are no longer _Military_ intelligence services. Although the military do have some intelligence services of their own, most of these things are handled by MI5/6. > Officially they are know as the Security Services, but the are quite happy to be known as MI5/6 considering the abbreviation that would be used (ie **S** ecurity **S** ervice). > > MI5 even has it’s own web site [her.](http://www.mi5.gov.uk/) Nearly, MI5 became Security Service or SS MI6 became Special Inteligence Service or SIS though the MI notations for these two are still comonly used. As for a cite, I used to work at GCHQ 😉 ---
**Author:** ![Bytegeist](https://avatars.discourse-cdn.com/v4/letter/b/9dc877/32.png) [@Bytegeist](https://boards.straightdope.com/u/Bytegeist)\ **Post date:** [August 25, 2005, 3:27pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/9 "2005-08-25T15:27:36Z")
A somewhat amusing thing happened a few weeks back… I was listening to a talk show on NPR. The segment was about the recent London bombings, and the interviewer was about to bring in an intelligence expert on the phone from England. She (the host) kept saying “M-fifteen” for the name of this agency. And she kept calling it that for the first couple minutes of the interview. The interview-ee was gracious enough not to correct her point-blank. Eventually she caught on, though you could kind of tell she didn’t know what the hell “MI-5” was supposed to be when he was first discussing it. At some point the light bulb lit up (or maybe someone shouted into her earpiece), and she just suddenly started using the proper name, without remarking on the change. The moral of the story? There are two actually. (1) Know the names of things before you go on the air, and (2) never use sans-serif typefaces to convey anything important. ---
**Author:** ![Mk\_VII](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)\ **Post date:** [August 25, 2005, 7:08pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/10 "2005-08-25T19:08:26Z")
‘Saturday at M.I.9’ was Airey Neave [codename Saturday] 's book about running an escapers help chain in WW2. Neave had previously escaped himself from Oflag IVc. ---
**Author:** ![Crandolph](https://avatars.discourse-cdn.com/v4/letter/c/7cd45c/32.png) [@Crandolph](https://boards.straightdope.com/u/Crandolph)\ **Post date:** [August 25, 2005, 7:30pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/11 "2005-08-25T19:30:32Z")
> [@bonzer](#): > > MI 18 Unknown Given that we know the others, you have to figure this is the one to really worry about… ---
**Author:** ![garius](https://avatars.discourse-cdn.com/v4/letter/g/e19b73/32.png) [@garius](https://boards.straightdope.com/u/garius)\ **Post date:** [August 25, 2005, 7:34pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/12 "2005-08-25T19:34:32Z")
> [@](#): > > ‘Saturday at M.I.9’ was Airey Neave [codename Saturday] 's book about running an escapers help chain in WW2. Neave had previously escaped himself from Oflag IVc. Blimey - i’ve never met anyone else who’s actually read that 😃 Rather good book actually. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 25, 2005, 7:48pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/13 "2005-08-25T19:48:02Z")
MI.9 is mentioned in passing in Tom Sharpe’s _Ancestral Vices_. One of the characters manages a factory where sex toys are made. He’s managed to keep the operation very discreet because the employees sign the Official Secrets act. It turns out MI.9 has a standing order for dildos and other kinky gear as a means to encourage (then) Cold War defectors. [sub] Hmph, no takers for “business”? That was a damn fine joke[/sub] ---
**Author:** ![Mycroft\_H](https://avatars.discourse-cdn.com/v4/letter/m/898d66/32.png) [@Mycroft\_H](https://boards.straightdope.com/u/Mycroft_H)\ **Post date:** [August 25, 2005, 8:52pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/14 "2005-08-25T20:52:05Z")
> [@bonzer](#): > > MI X Recruitment I’m disappointed MI-X wasn’t involved in UFOs, alien abductions and preventing world takeover. ---
**Author:** ![Bippy\_the\_Beardless](https://avatars.discourse-cdn.com/v4/letter/b/ac8455/32.png) [@Bippy\_the\_Beardless](https://boards.straightdope.com/u/Bippy_the_Beardless)\ **Post date:** [August 25, 2005, 9:45pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/15 "2005-08-25T21:45:25Z")
> [@Mycroft H.](#): > > I’m disappointed MI-X wasn’t involved in UFOs, alien abductions and preventing world takeover. It doesn’t say who or what MI-X are recruiting does it? ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 25, 2005, 10:23pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/16 "2005-08-25T22:23:21Z")
> [@Bytegeist](#): > > At some point the light bulb lit up (or maybe someone shouted into her earpiece), and she just suddenly started using the proper name, without remarking on the change. A more likely explanation is that a less-dumb producer frantically scribbled “IT’S EM-EYE-FIVE!” on a piece of paper and held it up to the window of the broadcast booth. 😉 ---
**Author:** ![WotNot](https://avatars.discourse-cdn.com/v4/letter/w/e19b73/32.png) [@WotNot](https://boards.straightdope.com/u/WotNot)\ **Post date:** [August 26, 2005, 9:14am UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/17 "2005-08-26T09:14:23Z")
> [@Mycroft H.](#): > > I’m disappointed MI-X wasn’t involved in UFOs, alien abductions and preventing world takeover. No, that would be DI 55. ---
**Author:** ![Big\_Whistle](https://avatars.discourse-cdn.com/v4/letter/b/5f9b8f/32.png) [@Big\_Whistle](https://boards.straightdope.com/u/Big_Whistle)\ **Post date:** [August 26, 2005, 12:22pm UTC](https://boards.straightdope.com/t/what-does-m-i-5-mean/318509/18 "2005-08-26T12:22:35Z")
Thought it was A-51. 😉