This is a theory from the very top of the civil service and diplomatic corps.
It’s an absolute classic of the British establishment.
In recent months Sedwill has told friends that he would like to be named as British ambassador to Washington—as part of a deal to quit at the end of Johnson’s transition to PM.
So who has it in for Sedwill?
The theory is that Williamson leaked the Darroch cables in revenge for Sedwill advising May to sack him.
So true establishment intrigue.