It is a long-standing tradition in detective work that when you are trying to crack a suspect under questioning, you need two interrogators; one to play soft man, one to play hard man. The first appears as a friend, and induces a sense of reassurance. The other closes in for the kill.

Yesterday Alex Salmond faced the combined techniques of a team which gave the old one-two treatment, leaving him distinctly stirred and not a little shaken.

First in, with a line that ran something like: “Listen, chummy, you’ve been a naughty boy, but if you tell us exactly what happened, we’ll see what we can do for you,” was Annabel Goldie, the Tory leader. Now, Ms Goldie is generally held to be a nononsense woman, and Mr Salmond must have felt he was simply going to be given a bit of a dressing down and warned about sharpening up his act.

Gradually, however, it emerged that he was suspected of misdeeds unbecoming to a First Minister, and was being softened up for the kind of treatment more familiar to the CIA than the parliamentary chamber at Holyrood.

Why, Ms Goldie wanted to know, had he met the developers of the multimillion pound Donald Trump golf project in Aberdeen during the critical four-day period leading up to the decision to call in the project, thus circumventing the local council? Was this not contrary to the ministerial code? And could it not be seen as prejudicial to the process?

A bit of squirming now went on. Mr Salmond does not normally squirm, but there was no other word to describe the way he answered. He had already met the objectors to the Trump plan, he said, so as a constituency MSP he was entitled, nay required, to see the other side, too. He had been advised that he was not allowed to say anything about the application. He had followed that“ to the letter. “Can I go now?”, his expression seemed to say.

Not so fast, was the answer. This was not “evenhanded, it was cack-handed,” said Ms Goldie severely. “It was either ignorance or arrogance. Ignorance is not a word with which I associate the First Minister.”

Ouch. It hurt, of course it hurt, but what followed was worse. Nicol Stephen, the Liberal Democrat leader, now stepped into the cell, slammed the door behind him and advanced in menacing style towards the prisoner. Metaphorically whipping the cigarette from between the suspect’s lips, and snatching away the cup of coffee, Mr Stephen asked him: “Were there any Trump representatives in the planner’s office at the time?”

This is the point where, in normal circumstances, you refuse to answer any more questions without your solicitor being present, or alternatively fall back on giving just your name, rank and serial number.

Instead Mr Salmond said: “I wisnae there.” Or rather: “I wasn’t there at the time,” which was not, of course, the question he had been asked. The point, rather, was whether the Trump men had been present when the Executive’s chief planning official was there. Mr Stephen’s eyes narrowed to thin slits of suspicion. This, he snarled, “smells of sleaze.”

In most interrogations, there is that moment when the door slams, the footsteps echo down the corridor, and the prisoner is left, miserably, to wonder what the next session will bring. Will it be the reassuring but vaguely menacing tones of Obergruppenfuehrer Goldie, or the sinister, scarred features of the Gestapo officer Stephen? Time, perhaps, to see whether that escape tunnel is still functioning.

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