Operation Gibbon

Gibbon was a covert operation in which Alec Palmer was involved. The Eleventh Doctor called it "the one with the carrier pigeons". (TV: Hide)

Behind the scenes
Although Hide never makes a wholly unambiguous reference to World War II, this reference in conjunction with mentions of the "Baker Street Irregulars", "U-boat operations in the North Sea" and the sabotage of "railway lines across Europe" seem to point to the real life Operation Gibbon of 1942, in which British forces attempted to "establish and organise a secret new carrier pigeon communications network" in Belgium, in support of the Special Operations Executive. Of course, Hide comes nowhere close to this level of definition, refusing to even name the year, or even war, in which the operation occurred.