I have a slightly different, and probably misguided, take on Starmer/Mandelson.
The Washington posting is the biggest one of all. It needs a really good and effective Ambassador. Particularly with erratic Trump in the White House.
Starmer increasingly recognises that present Labour is devoid of talent. So he’s reaching back to Blairites for help. He thinks they’re smart, experienced and battle hardened. Which is true enough in some ways, especially of Mandelson. But the track record obscured Starmer’s - already very limited - judgement, and he dismissed every warning sign.
And…car crash.
That’s my theory anyway. However you cut it, though, Starmer’s a bust and there must now be traction for a behind the scenes campaign to get rid of him.