I have just been on the phone with a shadow cabinet minister who said "it’s like something from The Thick Of It" because, they claimed, Jenrick "left his resignation speech printed out and hanging around" and "someone got hold of it".
This shadow minister added that he had sat next to Jenrick at yesterday’s meeting of the shadow cabinet and "he was playing nicely, I had no idea".
At a recent Tory away day, I am told, he had also been "contributing normally" with no indication a defection might be imminent.
So why has this happened?
"He has been overwhelmed by personal ambition in a Macbeth type way" his former colleague claimed.
"Kemi is getting better and his ambition wasn’t being sated. And he’s lost his mind."
Tellingly, a few hours on from this story breaking, we have heard nothing from Robert Jenrick, to hear his side of the story, while plenty of others drip sharp words into reporters’ ears.
Above from BBC