"In government you are pressed by the security agencies. They come to you with very good information and they say 'you need to do something'. So you do need the breath of scepticism, not cynicism, breathing on them. You need to be able to take a step back. If you don't have this, you can find yourself being propelled in a particular direction."

These wise – and honest – words from David Blunkett, the former Labour home secretary, in an interview with the Guardian, reflect the pressure the spooks have placed on ministers, home secretaries in particular.

It was a welcome reminder of a phenomenon that is far from new. The widely respected reforming Labour home secretary, Roy Jenkins, told MPs during a Commons debate on 3 December 1986 that "spies and counter-spies are, entirely unfitted to judge between what is subversion and what is legitimate dissent."

Jenkins continued: "I am sure that there is some need for a continuing specialised agency to deal with counter-espionage. Perhaps we can exaggerate the role of such an agency by saying that it should be given the highest national priority, but there should certainly be one in place that is efficient and trusted. That activity must now be subject to more political supervision".

Jenkins was said by his advisers that he felt somehow "tarnished" when he dealt with the spooks and tried to avoid doing so as much as possible.

In February that year, 1986, James Callaghan, home secretary before he succeeded Harold Wilson as prime minister, was asked by the Commons treasury committee, about whether the security services were out of control.

He replied: "I think that depends on whether the prime minister exercises such control...If it means do they take initatives of their own kind without clearing everything with a minister, if it means that, the answer is yes of course they take such initsatives".

Callaghan added: "They sometimes put to a minister actions which they think he will regard as repugnant but nevertheless they hope he will agree and the answer will be yes. Then it depends on the minister, whether he is sufficiently alert to say no to those particular questions".

Edward Heath, told the Commons during a debate in January 1988 on one of the first of many attempts to reform the Official Secrets Act how he "met people in the security services who talked the most ridiculous nonsense."

The former Tory prime minister told the Commons: " If some of them were on a tube and saw someone reading the Daily Mirror, they would say, 'Get after him, that is dangerous. We must find out where he bought it'".

It is so much easier now when the spooks, and GCHQ in particular, have so much technology at their command to carry out widespread intelligence-gathering operations without telling ministers what they are up to, let alone asking them for permission to do it .