"I see no way that you can continue in post, but without a formal mechanism to remove you it seems that the only way that this is... possible is for those of us who remain in Cabinet to force your hand," Donelan wrote in a resignation letter, saying she had "pleaded" with Johnson on Wednesday to resign.
"You have put us in an impossible situation... as someone who values integrity above all else, I have no choice."
(Reporting by Muvija M, writing by Alistair Smout, editing by William James)
