Pressure is building up in the Tory party, and without a release valve an explosion is on the cards.

Towards the end of last year, conventional wisdom held that Theresa May’s MPs were prepared to put up with her for fear of something worse – namely, a general election that could see Labour winning the keys to Downing Street. But in recent weeks, this uneasy compromise appears to have frayed. Rebellion is spilling out into the open.

Over the weekend, former Tory party chairman Grant Shapps, already the driving force behind a failed coup last year, called on May to set out her timetable for departure. Yesterday, former minister Robert Halfon called for government policy to be shaped by “lions not tortoises”.

He didn’t explicitly accuse the PM of having a shell on her back, but the implication was clear.

Meanwhile, Heidi Allen took to Twitter to demand the government “get a grip and lead” while her colleague Nigel Mills said May had failed to deliver on her promise to tackle burning injustices – in a direct reference to the pledge May made on the steps of Downing Street when she took office. That MPs feel they have the need (and the confidence) to air such criticism in public is telling.

To this mix of toxicity and desperation we can add the growing internal rows over Brexit: its path and destination are now subject to open debate and potential parliamentary rebellion. Yesterday, Cabinet Office minister David Lidington urged his colleagues to “come together in a spirit of mutual respect” ahead of the next crucial round of Brexit talks.

His plea follows a bust-up between chancellor Philip Hammond, who suggested in Davos that very little will change between the UK and the EU after Brexit, and Jacob Rees-Mogg, who insists that everything changes.

The two MPs represent opposite wings of the internal Tory debate, and it is for May to unite the warring tribes. But is she capable of doing so? If she can’t bring them together, she at least has to pick a side and run with it. Britain’s future relationship with the EU cannot be fudged indefinitely.

Never mind Tory MPs, it is business leaders and investors who need the clarity. May must set out a vision, and do so before she loses the authority to deliver it.

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