Amber Rudd has quit the Cabinet and resigned the Tory whip. Rudd’s departure deepens the split in the Tory party and will be a particular blow to Boris Johnson; the pair have always got on well personally despite their very different views on Brexit.

What will worry Number 10 is that Rudd might start something of a domino effect. There are, as I said in the Sun this morning, several Cabinet Ministers who are worried about the government’s direction and irritated at not being more involved in Number 10’s decision making. I hear that others might follow her out of the door in the next 48 hours, as we discuss in the latest podcast (below)

Rudd backed Remain in the referendum and Jeremy Hunt for the Tory leadership. In this respect, she was an odd fit for Boris Johnson’s Cabinet. Colleagues say that at the first meeting of the new Cabinet she looked around the table very uneasily as she sized up the new grouping. But Rudd gets on with Boris Johnson personally and is a pragmatist. She was prepared to commit to the October 31st ‘do or die’ deadline on the grounds that something was needed to break the logjam. But she was, as her appearance on the Women with Balls podcast made clear, deeply uncomfortable with the decision to remove the whip from the Tory rebels. Her determination to seek an assurance from Boris Johnson that any Tory MP who voted against a deal would also have the whip removed was another sign of that.

Rudd has told Tim Shipman that one of the reasons she is resigning is that she doesn’t believe the government is really trying to get a deal with the EU. If Boris Johnson is to prevent more Cabinet resignations he is not only going to have to consult more but make clear what his alternative to the backstop is.

She gave a pretty good indication about her thinking to Katy Balls a few days ago. Here’s Katy’s podcast, and her answer is about 25 mins in.