Just last week, Blackford was bullish about his future when asked by this newspaper whether he was confident he retained the confidence of the majority of SNP MPs, claiming he would lead the SNP out of Westminster. That lasted eight days.
Ahead of his resignation statement, released just before lunchtime on Thursday, there had been growing rumours about his future. A story in March by the Politico website claimed Mr Blackford would stand down, but was swiftly rejected by the man himself.
The summer saw heightened tensions among MPs following the disastrous handling of sexual harassment claims against the SNP chief whip, Patrick Grady, and the MP Patricia Gibson. The Grady affair, in which a leaked recording of a group meeting showed Mr Blackford calling on MPs to support the disgraced politician, was deeply damaging.
It undermined not only the attacks on Boris Johnson around integrity and accountability, but also the zero tolerance stance of Sturgeon towards sexual misconduct. It raised question marks about his judgement and ultimately his suitability for the role.
Two weeks ago, The Times reported Blackford was to face a coup from Stephen Flynn, a young upstart MP and rising star. But this coup collapsed as soon as it became public knowledge. Blackford, a man who has diced with being defenestrated before, had seemingly escaped again.
His departure, now assured, is a big moment for the SNP. He has been in post since 2017 and is, alongside Sturgeon, the leading public face on Scottish independence, especially in England. That influence on voters should not be underestimated given he was regularly on TV.
But, much like with his boss to whom he is fiercely loyal, there appeared to be a limited pool of willing replacements. Succession planning has been this SNP generation’s biggest failing. Flynn will get the top job if he stands, but is the SNP ready for that generational shift?
A fresh start he may be, but that does not guarantee success.
Blackford’s resignation is the first serious changing of the guard in half a decade. It’s the first sign the Sturgeon era is ending.