The number 24.20.3 is found on the billboard.
This site also mentions something called [[Operation Chip Sweep]], which led to another website, also apparently based in England.
also found on this site.
== Notes ==
* [http://www.met.police.uk/history/brixton_riots.htm Operation Swamp 81] refers to an actual plainclothes police operation and related riots in Brixton in 1981. Operation Swamp 0000 seems to be named after this historical event.