THE fact that Stewart Hosie, the Depute Leader of the Scottish National Party, made no mention in his letter of resignation of his proposed leadership of the party’s summer drive for independence is an indication of the kind of political impact the events surrounding him may have.

As the First Minister acknowledged in her reply to him, Mr Hosie has been an effective player for the SNP, not least in his work on the 2015 and 2016 manifestos, which means that if he does step back from the summer campaign on independence, there could be a significant impact on the party’s political strategy in the near future, and its effectiveness.

The appointment of someone else to the important role is also no guarantee that the effects of the resignation of Mr Hosie will fade. Indeed, as a hugely experienced politician, the First Minister knows that events such as Mr Hosie’s departure can be the beginning of a narrative that is hard to shake. She will also know that, tolerant as they are in certain respects, the electorate is quick to turn against politicians it sees as embarrassing or hypocritical.

The fact that Mr Hosie has resigned is also an acknowledgment of the fact that, although the breakdown of the marriage of an MP should usually be a matter only for the parties involved, there was a political element to the affair from the start. Mr Hosie is the SNP’s deputy leader and his wife Shona Robison is a close friend of the First Minister so it was inevitable that the deputy leader’s behaviour would put Nicola Sturgeon in an awkward position. The party will hope that the awkwardness has now been resolved by Mr Hosie stepping down.

But in the longer term, there is another bigger test ahead for the SNP. The investigations into the financial affairs of Michelle Thomson and Natalie McGarry have already inflicted damage, and the resignation of Mr Hosie is a further setback, but to what extent the damage can be limited will depend on what the First Minister does next. The fact that she has publicly stood by her friend Shona Robison does her credit, but the much harder job ahead is ensuring that her MPs – once such a source of pride for the SNP - avoid doing anything else to damage the party’s reputation.