What on earth was Catherine Calderwood thinking?

Catherine Calderwood was the face of Scotland's public advice campaign - advice she was not following herself

What on earth was she thinking? This was either grossly naive, achingly foolish or staggeringly arrogant. And either way the chief medical officer had to go.

I have heard it said - indeed a listener made this point on the wireless this morning - that Dr Catherine Calderwood should be forgiven a mistake.

Had not journalists, we were challenged, made mistakes on occasion?

They have indeed. An ample sufficiency of errors. But this mistake was of a distinct and different calibre.

• Calderwood resigns over coronavirus lockdown trips

Dr Calderwood was not a bystander in this crisis. Not a disinterested observer, however prominent. Not a remote analyst.

She was the public face of a campaign to persuade the public to stay at home. She delivered this message, repeatedly, in sonorous and sententious tones. And then she neglected those guidelines in her personal life, travelling not once but twice from Edinburgh to her family's second home in Fife.

This is comparable to an individual who is leading an initiative to persuade the public of the merits of vegetarianism, who then indulges in a T-bone with a side order of bacon.

In fact, it is worse. It was Dr Calderwood herself who echoed the mantra of the Scottish and UK authorities that by staying at home we would helping to protect the NHS - and thus to save lives. To save lives.

Addressing the issue at her briefing today, the first minister contrived admirably to remain cool in the face of tough media questioning, while simultaneously declaring her intention to move on.

Asked about the information given to her by Dr Calderwood, Ms Sturgeon said it was possible for more than one thing to be true at once.

For a moment, I was back with Alice in Wonderland, or rather Through the Looking Glass, contemplating six impossible things before breakfast.

However, I know what she means. Ms Sturgeon was initially given limited information, dealing with a single weekend visit, said to be intended to secure the Fife property.

It then emerged that there had been another visit, on a different weekend. This, understandably, excited further questions from the wicked media.

Ms Sturgeon argued that the number of visits was immaterial. There was no justification for the CMO in leaving Edinburgh at all. It was indefensible, and she did not defend it.

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Then came an intriguing argument from the FM. Were the times normal, were she simply weighing political considerations, were she practising the doctrine of spin and news management, she would probably have dispensed with Dr Calderwood immediately the story broke.

But the times are very far from normal. She was conflicted. On the one hand, she did not want to lose "invaluable" medical advice, to lose a key member of her team who, like her, had been working round the clock.

That was the case for continuity. On the other hand, there was the argument about the potential damage which might be done to public confidence. Continuity versus confidence.

I grasp this dilemma, which is real. In governments, in life, decisions are rarely pure and never simple. One has to balance the likely impact.

So the initial solution was that Dr Calderwood would remain in post, would continue to give medical advice - but would withdraw from the public-facing aspects of her job, would withdraw from fronting the campaign.

On the wireless this morning, I was somewhat caustic about this option. Was it feasible, I asked, that Dr Calderwood would stay in office, still taking her salary, still offering advice but somehow hidden behind the scenes in Edinburgh and presumably still longing for the sun-kissed shores of Fife and her second home.

As it turns out, it was not. So what changed? Public anger, voiced through the media, through social media, and directly to MSPs and ministers, including the first minister.

That anger welled up. Why were we, the public, expected to obey advice from a medic who seemingly neglected it herself? The fact that she practised social distancing while in the Kingdom made no difference. Folk were furious - and made that clear.

At which point, for Ms Sturgeon, the balance shifted. There was now a palpable possibility that folk would begin to neglect or even reject the advice, because of the original source.

The FM then had a further lengthy conversation with the CMO - and the outcome was departure for Dr Calderwood. Nicola Sturgeon chose to protect the message and dispense with the messenger.

Further, with opposition leaders circling, it became evident that this was turning into a question of the FM's own judgement, not that of her medical adviser. That too was a step too far.

Dr Gregor Smith is to stand in as chief medical officer in the interim

Be clear. It is possible to feel personal empathy for Dr Calderwood, within limits. Until now, she appeared to be a diligent, dedicated public servant, committed to the cause.

Until now. She made what she acknowledges to be a grave mistake and has suffered the consequences.

How about mid to long term damage? Very hard to assess. It all depends how Nicola Sturgeon, her health secretary and the deputy CMO perform in the days ahead.

At the briefing today, the deputy - Dr Gregor Smith - made rather a good start. His briefing was contained and concise, solid rather than spectacular. Dr Cameron, not Dr Finlay.

Indeed, he presented himself as the apogee of a sound Scottish GP. Albeit one who is apparently a fan of Iron Maiden.

I think it likely, on balance, that this too will pass. That the crisis is so severe, so overwhelming, that it will demand that our attention and our endeavours do indeed move on from the case of the departing CMO.