Amber Rudd seemed slowly to be escaping the worst of her troubles yesterday.  Now she has gone.  Did she come to consider her position too vulnerable, after all?  Has she simply had enough? Or is there some twist to the tale – some as yet undiscovered Home Office document or exchange – that we don’t yet know about?  At the moment, it looks as though the second is the case, but we will doubtless find out more in due course.

So Michael Fallon, Priti Patel, Damian Green and now Rudd have left the Cabinet that Theresa May formed last summer.  That’s a departure rate of almost one of its members every three months – an indication of this Government’s essential fragility.  The Prime Minister will not have wanted to lose a senior former Remainer from her Cabinet who can now cause her Brexit trouble – and perhaps tell recent tales of dealing with both May’s Home Office legacy and her internal management of leaving the EU.

Who will replace Rudd?  If the Prime Minister goes for a loyal woman Remainer, the person who best fits that bill is Karen Bradley.  Jeremy Hunt is a big figure, and surely couldn’t again refuse to move from health.  Sajid Javid would be a bold change.  If May sends for a leaver, she could prise one of the big four out of position – David Davis, Liam Fox, Michael Gove and Boris Johnson – but she only trusts the second of those.  Then there is always Chris Grayling, who nearly made Party Chairman.  But guesswork is a mug’s game.

Behind the speculation about personalities is a choice about policy.  In May’s ideal, Rudd’s replacement will be loyal to Downing Street, and keep the Cabinet balance she wants between men and women, and Remainers and Leavers.  But the Prime Minister will also want this person to march in step with her on immigration.  In a nutshell, she will not want a new Home Secretary whose approach is instinctively liberal, or more attuned to the position of business than that of voters overall.

So we are set for a mini-reshuffle in the week of the local elections, and of the “war Cabinet” meeting on options for leaving the Customs Union.  The Prime Minister will need to handle it more smoothly than the dreadful day one of January’s bigger changes.  Finally, Rudd’s resignation also takes a leading former Remain future leadership candidate from the Cabinet – and out of contention, at least for the moment.  It is not obvious who replaces her.