If a Minister resigns, Downing Street and the Whips hope a) that he or she is unpopular with their colleagues – or at least not popular; and b) that she is easy to replace.

Neither of these conditions apply in the case of Tracey Crouch – who has just quit the Government over a delay to a cut in maximum stakes for fixed odds betting machines.  The former Sports Minister is liked by most of her colleagues and was rated as a Minister: she knows a lot about sport and is an enthuasiast for it.  These qualities are more rare among Ministers than they might be.

The Treasury will doubtless now be cast as dodgy and duplicitous, stealthily putting back the implementation of a policy that it has never liked.  It will surely claim that the timetable hasn’t slipped and Crouch will argue that it has.  She apparently said publicly that the reduction would come into force in April.  Philip Hammond set the month as next October during the course of the Budget.

Rumours of Crouch’s resignation have been floating about all day, having first appeared in the Daily Telegraph this morning, and we learn more in due course about what will have been a three way exchange between Crouch, the Treasury and Number Ten – or four-way, if you count in her former Secretary of State, Jeremy Wright.

Her resignation letter claims that Downing Street has been asleep on the job, and missed the Treasury reneging on guarantees previously given.  Well, actually, it doesn’t quite say that in terms, but such is the implication of Crouch writing that Theresa May’s “personal support” was “incredibly helpful” and evidence of a real willingess to support “vulnerable people against the power of big business”.

The former Minister attributes the delay to “commitments made by others to those with registered interests”.  Questions will be asked, as they invariably are, about how this political banana skin wasn’t spotted lurking on the floor.  Though maybe the Government will simply gird its collective loins, and press on.

Crouch threw herself heart and soul into the campaign for reduction, and will have taken this week’s news as a breach of trust.  Outside Westminster, the news will make little impact on a Budget, and its aftermath, that has gone more or less according to plan.  Inside, it may not be quite the same story.  The Government has no majority, after all.