Something has finally snapped inside the Conservative party. After months of Tory remainers inside government mostly keeping their heads down and crossing their fingers, telling themselves Theresa May would never knowingly embrace a no-deal Brexit no matter what she felt compelled to threaten in public, this week’s concerted threat of mass resignations suggests the dam has broken.

On Tuesday morning, May’s good friend Margot James joined fellow ministers Claire Perry and Richard Harrington in co-authoring a piece imploring the prime minister to extend article 50 if a Brexit deal isn’t agreed by 13 March. That follows a similar move over the weekend by Amber Rudd – another long-term May ally – and fellow cabinet ministers David Gauke and Greg Clark which has made the prospect of an extension increasingly likely, with up to 15 ministers said to be ready to resign or be sacked rather than go along with a no-deal Brexit they regard as an unmitigated disaster. In other words, the Tory hard right no longer has a monopoly on publicly threatening to quit. And much as Labour voters will largely welcome Jeremy Corbyn’s last-minute conversion to the cause of supporting a second referendum, which still looks unlikely to happen, it’s still a revolt within the governing party that has the greatest chance of breaking the logjam.

The Tory rebels don’t all necessarily want to stop Brexit. But they do want May to make delaying Brexit, rather than crashing out with no deal, the default option if her deal fails to pass parliament. If she won’t then they are likely to support Yvette Cooper and Oliver Letwin’s amendment for a delay instead. That not only changes the parliamentary maths, but also begins to reverse something that has helped a relatively small group of hard Brexiters hold the country hostage in the first place; the fact that the rest of the party did not unite and fight back against the radicals. The thing about moderate Conservative MPs is that they are by nature moderate and conservative, preferring to operate by consensus and behind the scenes rather than staging noisy public showdowns. But the speed at which the cliff edge is approaching, coupled with nerve-jangling uncertainty about whether May could actually be persuaded to leap off it, has changed that.

Why now? Some suspect the machiavellian hand of No 10, getting friendly ministers to provide her with an alibi for extending article 50, although that would suggest a degree of cunning not always obvious in Downing Street’s Brexit strategy.

Others will credit Anna Soubry, Heidi Allen and Sarah Wollaston’s decision to resign from the Conservative party, forcing MPs who wouldn’t personally jump ship but can hardly disagree with their newly independent friends’ arguments to think about what they are going to do instead.

But more broadly this looks like the Conservative party gradually realising that there is nothing remotely conservative in the small ‘c’ sense about a project that means stockpiling medicine and prompting the Institute of Directors to say it has lost faith in the political process. Or to put it more simply, they just don’t think “fuck business” (in the immortal words of Boris Johnson) is a winning Conservative slogan. If anything, the surprise is it’s taken the mouse this long to roar.

• Gaby Hinsliff is a Guardian columnist