When it comes to Mr Corbyn and Mrs May, the big difference between the two leaders, says the Guardian, is whether it makes sense to threaten to walk away from Brexit negotiations if EU demands become too onerous.

Labour says the walk-away strategy is absurd. "Crashing out would the worst possible outcome", says Corbyn. "There is no such thing as no deal. No deal is in fact a bad deal; it is the worst of all deals".

Mrs May, on the other hand, says the Guardian, is doubling down on her claim that only an enthusiastic embrace of the alternative "no-deal" scenario will help convince EU negotiators that Britain is serious about leaving and encourage them to make the necessary compromises.

If this election is all (or mainly) about Brexit – as Mrs May said it was – then this is the dividing line: deal, or no deal. Should we elect a president (for, in truth, that's what we're electing) who is committed to bringing back a settlement, or one who will scorch the earth if she doesn't get what she wants.

Which side of the line electors take is up to them, but it beholds advocates of either position to be honest about what each involves. At best, a "deal" gives us a breathing space, an opportunity to work for a sustainable, long-term solution. The price ticket, though, is probably going to be eye-watering and other concessions will cause more than a few palpitations in high places (and low).

On the other side, there are those who seems unable to grasp the penalty of walking away - whether by accident or design. Most recent of the equivocators is Allie Renison, masterfully dissected by Pete. To be a little bit fair, she is trying to be tactful to the Muppets on Conservative Home, telling them that the "absence of a comprehensive agreement would not be apocalyptic, but it would involve many complexities".

Why she should treat their structured dishonesty with kid gloves is not explained, but at least she seems to have recognised that most of the CH contributors ended up sketching out a series of deals which the two sides could come to agreement on, rather than setting out the implications of relying solely on multilateral-level agreements. In other words. their "no deal" scenarios involved collecting together multiple smaller deals.

This roundabout "just-don’t-call-it-a-free-trade-agreement" way of arguing for a deal, she found perplexing – just as we did - although she mistakenly believes that Article 50 presents an opportunity to lay the foundations for a free trade agreement, something that is simply not on the cards.

The thing is, though, if we don't get a comprehensive agreement – which we won't – the best possible outcome is to arrive at a less than comprehensive agreement. In that event, we have to ask which chunks of meat would have to be thrown off the sledge, just to get a partial deal. Are we to sacrifice the chemical industry, pharmaceuticals, the food sector – or what?

Interestingly, as I started writing, up came piece from the home of the "no dealers", the Telegraph published a report headed "UK pharma sector faces 'crisis' without early Brexit deal".

This retails a publication by the European Medicines Agency (EMA), with the somewhat lengthy title of "Questions and Answers related to the United Kingdom's withdrawal from the European Union with regard to the medicinal products for human and veterinary use within the framework of the Centralised Procedure".

They don't do short in euro-land, but the message is clear. Should the UK leave the Single Market, as Mrs May wants, the so-called "market authorisations" held by UK pharmaceutical companies – which enable medicines to be sold throughout the EEA – have to be transferred to "a holder established in the Union (EEA) ".

This is by no means a simple process (nor cheap) and, with other changes, has the Association of the British Pharmaceutical Industry (ABPI) very worried indeed.

Dr Virginia Acha, executive director of research, medical and innovation at ABPI, described the EMA's paper as the "opening chapter" in what she describes as a "crisis". She estimates that restructuring costs arising from leaving the Single Market UK would run to "hundreds of millions of pounds".

Dipping its foot in the issue, the Financial Times also notes that "medicines made in Britain will be treated as imports by the EU in the event of a "cliff-edge Brexit", but it isn't even close to the reality. This happens unless we stay in the Single Market via the EEA.

We wrote about this in January, but it's still not getting through. Once we break out of the Single Market, a lot of systems start falling apart. What affects the pharmaceutical industry will damage many others, not least the chemical industry, which is going to have a very hard time of it with REACH.

The Guardian, though, is wetting its knickers at the prospect of the UK dropping REACH and allowing the UK to become a "toxic dumping ground".

But, with over £20 billion of chemical exported annually to the EU, there is no way the chemical industry could even contemplate dropping REACH. Apart from prejudicing chemical sales, products made with unregistered chemicals would also be treated with suspicion by the EU.

The breakdown of the regulatory structure in the UK, therefore, would be a very serious affair, but then so will be our withdrawal from the Single Market, creating endless "complexities".

It is all very well for Allie Renison to talk glibly of these complexities, but when the pharmaceutical industry refers to them in terms of "crisis", this puts her complacency in perspective. Call it "catastrophic" or "apocalyptic", it amounts to the same thing. That's the certain outcome of a "no deal" scenario. It is also the effect of failing to reach a comprehensive deal within the time remaining, and failing to broker transitional arrangements.

Others, of course, dismiss the idea of equating "no deal" with scorched earth. They pretend that the earth will stay green, that their "no deal" scenario is a harmless lever which will, as the Guardian kindly confirms for us, encourage the EU negotiators to make the necessary compromises – giving us the impossible, that elusive trade deal. 

This can be presented as a gamble. But it's not. The EU is not going to make the fantasy concessions that Mrs May seems to want. The Commission could not have been clearer in stating its position, and has been remarkably consistent. Mrs May is not going to leverage any cracks. There is no gamble – just disaster.

With less than a week to go to the election, therefore, the choices are becoming clearer and what once seemed impossible is becoming part of our reality.

But if we find ourselves unable to vote for Corbyn in this presidential race, there is an equivalent block on voting for a woman who is taking her mandate for granted and is steadfastly refusing to give us any detail on how she intends to secure an acceptable Brexit.

Mrs May tells us that she is "confident" that under her (strong and stable) leadership, that "we can fulfil the promise of Brexit together and build a Britain that is stronger, fairer and even more prosperous than it is today". Unless or until she can tell us in some detail how she intends to do that, though, Corbyn looks a better bet.

Needless to say, any difference is only relative. As Sam Hooper so fluently describes, we are reaching the limits of tolerance of lightweight British politicians. There is a dividing line between us and the politicians that is evolving into something substantial.