Operation Anvil (Mau Mau Uprising) the reserves. The "Grey" grade was made up of prisoners believed to be passive Mau Mau sympatherisers though for whom strong evidence suggesting their true loyalties was lacking. The last category, "Black", was reserved for detainees identified by the hooded informers or the Special Branch of the Kenya Police as potentially violent insurgents or terrorists. A few may have been prosecuted by the government, but most were funneled through the "Pipeline", a system of work camps, decreasing in brutality until an individual was "re-educated" and deemed safe to release on a native reserve. Operation Anvil (Mau Mau Uprising) Operation Anvil
Mau Mau Uprising son—who, after confessing, joined screeners at Athi River Camp, later travelling throughout the Pipeline to assist in interrogations. Suspected informers and spies within a camp were treated in the time-honoured Mau Mau fashion: the preferred method of execution was strangulation then mutilation: "It was just like in the days before our detention", explained one Mau Mau member later. "We did not have our own jails to hold an informant in, so we would strangle him and then cut his tongue out." The end of 1955 also saw screeners being given a freer hand in interrogation, and harsher conditions than straightforward