A mere six weeks after it began, Jo Johnson¡¯s comeback as universities and science minister is over. After being reappointed to the post when the new prime minister, his brother Boris, entered Number 10, Jo Johnson today that in ¡°recent weeks I¡¯ve been torn between family loyalty and the national interest ¨C it¡¯s an unresolvable tension & time for others to take on my roles as MP & Minister¡±. His exit as minister is immediate, while he will stand down as an MP at the next election.

It always seemed baffling that Jo Johnson, an ardent campaigner for Remain in the EU referendum, who had warned that a no deal Brexit would ¡°inflict untold damage on our nation¡±, had ostensibly signed up to the commitment to back a no deal Brexit demanded of ministers in the new government.

Presumably, Jo Johnson ¨C who remained closely engaged with ÖйúAƬ policy after his first resignation over Brexit, as transport minister for the Theresa May government ¨C thought there were some key things he could achieve in the short term in the universities and science brief, notably helping to bury the Augar review and to revive post-study work visas for international students.

His exit inflicts a political wound on Boris Johnson and raises questions about some key policy issues in ÖйúAƬ.

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On the wider politics, one of the traumatic aspects for Jo Johnson in taking this decision must have been the knowledge that he was giving Labour an easy line of attack on his brother.

Angela Rayner, the shadow education secretary, said in a press release issued rapidly after the announcement: ¡°Boris Johnson poses such a threat that even his own brother doesn¡¯t trust him.¡±

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She added: ¡°We have now had four ÖйúAƬ ministers in two years ¨C just the latest sign of the chaos that the Tories have caused to education and the threat that a disastrous no deal Brexit poses to our colleges and universities.¡±

Of the last four Tory universities ministers, Greg Clark and Sam Gyimah have been expelled from the party this week for rebelling against the government, while Jo Johnson is to quit as an MP.

Boris Johnson¡¯s purge of Tory moderates from the party, after the rebels supported a bill to force the government to remove the immediate threat of a no deal Brexit, appears to have been the trigger for Jo Johnson¡¯s move.

ITV journalist Robert Peston that Jo Johnson had told colleagues ¡°how upset he was at purging of Tory MPs¡± like former education secretary Justine Greening and Ken Clarke, ¡°to whom he is closer politically in many ways than to his brother, especially on Brexit¡±.

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There were suggestions on Twitter that Jo Johnson may return to his old employer, the Financial Times, as editor.

In policy terms, Jo Johnson may have pretty well achieved his short-term goal of seeing off the Augar review¡¯s plan to lower fees to ?7,500, which universities feared would mean big funding cuts (Augar was not mentioned in the chancellor¡¯s spending review this week, which the last government had said would contain its response).

And there are suggestions that an announcement on the return of post-study work visas for international students, for which Jo Johnson had already laid much of the groundwork from the backbenches, is expected soon. Whether today¡¯s developments change that remains to be seen.

Jo Johnson¡¯s exit?comes as the Department for Education considers its response to?the review of the teaching excellence framework ¨C policy Jo Johnson personally created ¨C by Dame Shirley Pearce. The government has digested the review, which includes a consideration of the merits or otherwise of moving to a subject-level exercise.?But the process of publishing a response to the review will now be held up as someone patiently explains to the new minister what the TEF is.

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Given that Jo Johnson was the most pro-EU minister in the new government, his successor will inevitably bring a shift in attitudes on Brexit. A Brexiteer in the universities and science job would worry the sector, given its hopes that the government will be willing to pay the EU to join its research and Erasmus programmes after Brexit.

So we await the appointment of the next universities and science minister, assuming there is such an appointment given the likely proximity of an?election. Whoever they turn out to be,?recent history suggests that we shouldn¡¯t get too attached to them.

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John Morgan is deputy news editor at Times ÖйúAƬ.?