GCHQ

The Government Communications Headquarters (GCHQ) was, according to the Thirteenth Doctor, the biggest communications resource in the United Kingdom. On 1 January 2019, a Reconnaisance Dalek penetrated the GCHQ and commandeered its resources in an attempt to contact the Dalek Fleet, but was stopped by the Thirteenth Doctor and Team TARDIS. (TV: Resolution)

In early 2020, the Doctor suggested that C, head of MI6, ask his "mates" at GCHQ should he doubt the existence of extraterrestrial life. (TV: Spyfall)

Behind the scenes
Following the broadcast of Resolution, in which the GCHQ was attacked by a Dalek, the real-world establishment jokingly reported that they were back up and running once again.