These Tory defectors are the Thelma and Louise of British politics

At the end of Thelma & Louise, as the net closes in on the outlaws, Geena Davis’s character turns to her friend and says she doesn’t ever remember feeling this awake. The freedom they craved may be violent and volatile compared to the steady suburban unhappiness of the lives they left behind, but at least now it feels as if there’s something to live for.

There was a hint of something similar about a gleeful Heidi Allen declaring, as she left the Conservative party this week, that she was “tired of feeling numb” about politics; that she hadn’t felt this excited in years. The self-styled “three amigos” driving away from the Tories into an uncertain future as independents will no doubt have suffered their share of sleepless nights over this particular road trip. But compared with the rather grief-stricken press conference given by their colleagues leaving the Labour party, the excitement was palpable, and for a certain kind of female voter it’s undoubtedly infectious.

For these look like women you could kick off your heels and crack open a bottle with, if not quite go on a crime spree across the Midwest. They don’t seem to have much of a safety catch – within hours of leaving, Anna Soubry had suggested that Theresa May has a personal problem with immigration – and they bring sorely needed exuberance to the table. When politics is so laced with menace, so full of doom and purity tests, any counter-insurgency badly needs to look as if it might just occasionally be fun.

And if it’s hard to see how any of this can be corralled into a coherent political platform, given the defectors’ very real differences on economic policy, then we may be looking through the wrong end of a telescope. Some involved with The Independent Group (TIG) clearly do see it as an embryonic new centrist party, capable of standing candidates in general elections. But other Tiggers aren’t sure about throwing off the shackles of one party whip just to wear someone else’s. If Chuka Umunna comes across as a man permanently looking for something to lead, it’s easy to imagine Allen just racketing around parliament cheerfully raising hell for her chosen causes for as long as she gets the chance, while eschewing anything so old-fashioned as collective responsibility.

Fluidity is the hallmark of our times, as restless millennials bust gleefully out of boxes that confined previous generations. So it’s perhaps surprising that as the rigid boundaries around gender or sexuality collapse, political beliefs are policed with increasingly religious fervour. The power of the whip over MPs has been fading for years, yet still political identity cannot be allowed to be non-binary. You’re either a true believer – whether in Corbynism or in Brexit – or a treacherous, flibbertigibbet who must take personal responsibility for anything that now goes wrong. But what if this pressure to conform has driven people who don’t comfortably fit the mould to break it?

The obvious flaw in the analogy, of course, is that who people sleep with is entirely their business but a politician swapping ideological partners has public consequences. The British political system is built around voting not for individuals but for party manifestos – which is why even the highly charismatic tend to get steamrollered when standing as independents – for good reason. Manifestos are the mechanism by which voters can be sure of what they’re getting from a party, and whipping is the guarantee that MPs will deliver it. There are fascinating parallels between the bouncier Tiggers and Douglas Carswell’s argument in his book The End Of Politics, written before he defected from the Tories to Ukip to sitting as an independent, about an imagined future politics without the trappings of conventional parties. But while the idea was intellectually exciting, the practical pitfalls were daunting. It’s all very well for the writers of Thelma & Louise, who could end with the two women forever magically suspended in mid-flight off the edge of the canyon. Had we seen their bodies smashed to bits on the rocks, it would have been a very different film.

Yet as with Thelma & Louise, the wildness of what they’re attempting makes more sense in the context of what they’re escaping. If the ex-Tories seem perkier than the rather traumatised Labour refugees, it’s perhaps because they feel they’re getting out of a potentially toxic relationship early rather than waiting until it’s too late.

We’ll never know what would have happened in 2016 if Andrea Leadsom hadn’t voluntarily quit the Tory leadership race. But she deserves more credit than she gets for it, because however bad things are now they could be worse. Drunk on referendum victory, could grassroots Conservatives have picked the out-and-out Brexiter over the vastly more experienced (but remain-voting) Theresa May? Would we now have a prime minister Leadsom, flanked perhaps by chancellor Chris Grayling, leading us into a no-deal Brexit?

Certainly, smarter Tories were worried. They’d watched the ascent of Jeremy Corbyn and begun wondering if their own membership was capable of delivering a shock to the system. Since then, they’ve seen the emergence of a so-called “purple Momentum” – an organised push by former Ukip voters rejoining and agitating for the deselection of Tory moderates – and the Eurosceptic right in parliament solidifying into an organised caucus capable of getting a Jacob Rees-Mogg figure on the list for the next leadership contest. And they have watched as disorientated Labour colleagues clung on and desperately tried to make it work, only to be eaten alive by a resurgent left.

Evidently the three amigos don’t intend to sit around waiting to meet the same fate. And if this leap off a cliff ends as so many previous attempts at new parties have ended, they’re not so institutionalised that they couldn’t find something useful to do outside parliament. Let’s just hope the electorate, who in the event of some great centrist revolt failing would be left choosing between parties shorn of all their moderating influences, don’t end up as the wreckage at the bottom of the canyon.

• Gaby Hinsliff is a Guardian columnist