That this was one man’s stand against the prime minister seems plausible.
Had Sarwar been part of a co-ordinated effort to oust Keir Starmer, you would have thought other senior figures would have been lined up to back his call for the PM to stand down.
That said, I am told Sarwar did have conversations with many leading Labour figures over the weekend – including Wes Streeting, Angela Rayner and Lucy Powell – without sharing what he was about to do.
Those in Labour disillusioned with Starmer’s leadership at Westminster and Holyrood are operating on different timescales.
Those who want the PM’s job might prefer that he takes the blame for any electoral setbacks Labour suffers in May before making any big moves.
If you are fighting those elections in the hope of becoming Scotland’s next first minister and you believe Starmer is holding you back, May is too late.
That’s why Sarwar spoke out when he did and he believes that doing so brings him much closer to public opinion however much it complicates the internal politics of the Labour Party.
His calculation was that to do nothing was not an option and that maybe, just maybe, doing something bold could shift Labour’s position in opinion polls that suggest the party’s miles behind the SNP.
His political opponents and plenty within Labour think he has miscalculated and they might be right but that has yet to proven one way or the other.