[pjc50]

See discussion of "permanent state" passim: https://news.ycombinator.com/item?id=9902497

The security services have a large amount of operational discretion and privileged access to ministers. They have the ability to present secret "evidence" which cannot be publicly challenged.

Let's not forget that the CIA effectively ran the governments of several Latin American countries, and in the UK Northern Ireland was effectively governed by the police Special Branch.