It was supposed to be easy for Amber Rudd. All she had to do was turn up at a parliamentary committee and answer their questions on immigration policy, her responsibility as the Home Secretary. Unfortunately for Rudd, she was soon forced to resign with a personal apology to Parliament for “misleading the House”.

Whether she had wilfully or incompetently misled her colleagues is not especially the point. She had given incorrect information about the treatment of illegal immigrants at a time when the Windrush scandal was dominating Westminster. The two issues were conflated because the Windrush victims were being treated as if they were illegal immigrants when they were not, emotions were therefore understandably high, and to add some political seasoning the English council elections were coming up fast.

Rudd had either known about an internal memo that discussed how to increase the numbers of illegal immigrants being deported and forgot about it, or she had not read it – both acts of incompetence that at another time might have been forgiven. Or she had read the memo and intentionally sought to cover it up – an act of political chicanery and mendacity for which no apology could or would be accepted. Cock-up or conspiracy? You choose, but here’s the thing, Amber Rudd recognised she was the problem. She understood that she had been found out for incompetence or lying and that resigning was the right thing to do. It would also gave many people a sense that someone in authority was paying for the dreadful treatment of the Windrush generation that had happened over four decades and countless Home secretaries, with others contributing to their plight far more than she had time to. Rudd went because she knew it was the right thing to do.

First Minister of Scotland Nicola Sturgeon. Picture: Jeff J Mitchell/Getty Images

By comparison let us consider the behaviour of our First Minister Nicola Sturgeon. On many occasions the First Minister – she who holds the highest political office in our land – has been asked before her peers in Parliament if fracking would be or is banned by her government in Scotland. To say she has been unequivocal in her answers would be understatement, for that is not her style. On 5 October last year the Green MSP Mark Ruskell asked the following straightforward question:

“The fracking ban has rightly been met with celebration across Scotland, but there are concerns from communities and many SNP members that the ban is not yet legally watertight, as it merely extends a temporary brake on planning decisions. Will the First Minister get the ban properly over the line by putting it on the same footing as the ban on new nuclear power stations, and will she commit to using the licensing powers when they arrive?”

The First Minister gave him this direct response:

“The ban on new nuclear energy in Scotland is done through planning powers and that is exactly what we are proposing for the ban on fracking. Let me be clear, because to some ears, it will sound as if some members are dancing on the head of a pin: fracking is being banned in Scotland – end of story.” She later reiterated her point, saying: “Those who, like me, do not believe fracking should go ahead in Scotland should welcome the fact that fracking is banned in Scotland.” Fracking in Scotland is banned and that “fact” was made very plain in her trademark assertive tones just in case anyone might doubt her.

Just in case some people do not pay attention to what is said in Parliament, the First Minister went on and tweeted the following message on 17 October: “Scottish Government backs ban on fracking.”

A ban is a ban is a ban, you would be forgiven for thinking – especially when it is the First Minister telling not an inquisitive committee, not a curious media reporter but fellow members of the Scottish Parliament and beamed around the world by Holyrood’s internet broadcasters.

Last week, however, the First Minister was found to have “misled the House” or at least misled Holyrood and the whole nation as well – I really do not see any difference. Defending a legal challenge from ReachCHG and Ineos, the owners of the Grangemouth petrochemical plant who wish to explore the possibility of fracking in Scotland rather than ship four tankers worth of fracked gas over from the US, the Scottish Government’s advocate, James Mure, QC, told the Court of Session, “The concept of an effective ban is a gloss. It is the language of a press statement. What they have done is to announce a preferred position on the issue.”

So the ban is not a ban, it is a “preferred position”.

How does this differ from Amber Rudd telling a Commons committee there were no targets for deporting illegal immigrants when she had received a memo that appeared to contradict that fact?

The First Minister cannot be said to have found the wrong choice of words or made a slip of the tongue or been talking in general terms and not specifics, she was claiming for her government as a success, as a mark of pride that she had banned fracking.

Where does this leave us in trusting anything the First Minister says? Where does it leave the Green Party in supporting the First Minister and her minority administration? After all, they could probably achieve a fracking ban irrespective of who’s in power at Holyrood, they do not need to support Nicola Sturgeon or even the SNP to achieve that. They could insist she resigns for misleading them and everyone else, just as many insisted that Amber Rudd resign.

Nicola Sturgeon has apologised in the past when it suited her. She apologised in parliament for her personal misjudgment in asking a sheriff to consider alternatives to custody for a convicted fraudster, Abdul Rauf, whom she knew had previous convictions. At least on that occasion she was acting on behalf of a constituent. On fracking she was putting herself, her party and her government before the truth.

In one of the most important economic decisions of her tenure, the First Minister told everyone who would listen there is a fracking ban in Scotland and called it a “fact”. Her government’s advocate calls it a “gloss”. An apology is the least Nicola Sturgeon should give. The case for the First Minister’s resignation is cast iron. Does she have the self-awareness of Amber Rudd to do the right thing?

Brian Monteith: Case for Nicola Sturgeon resignation is '˜cast iron'