Nicola Sturgeon has faced some rocky times at First Minister’s Questions in the past, but can rarely have experienced as uncomfortable a session as she did yesterday.

The SNP leader struggled to give a convincing account of her role in the investigation of sexual misconduct allegations made against her predecessor Alex Salmond.

It was, or should have been, clear from the moment these allegations came to light that they were potentially explosive for the SNP itself and for the government.

Ms Sturgeon acknowledged this and won admirers initially by insisting that no-one – not even a man who had been in many ways her own mentor – could be above investigation. So how can she possibly not have realised that repeated unminuted meetings and phone calls between herself and Mr Salmond were fundamentally problematic? How can she continue to insist that meeting him to discuss a government investigation in the presence of a government employee was not a government business which should minuted? It stretches credulity.

How can the investigation have been allowed to be fatally compromised by a procedural error so early in the process? Is is no wonder she laboured to convince.

The partisan rumblings around the investigation, it must be said, also stretch credibility. As Ms Sturgeon points out, she appears to be being accused of both plotting against Mr Salmond and colluding with him. The truth is this is likely more cock up than conspiracy.

But it is the biggest crisis the current first minister has faced, and with multiple investigations of her role looming, it is becoming a morass from which escape can only be time-consuming and damaging. Meanwhile the women must now await a police Scotland investigation or their allegations risk being sidelined.

It is all a potentially catastrophic distraction as Brexit looms. As an apparently inept UK government is steering us towards a quite different crisis. Scotland needs its government and first minister to be paying full attention.