I’ve been predicting and hoping for an exit date for about two years now, only to be frustrated time and time again.

So forgive me if I point out that, like Brexit itself, what we’ve got so far is a hollow declaration of intent and not the desired outcome. Theresa May has, so far, announced only that she plans to quit as Tory leader on June 7, but will remain Prime Minister until her successor is elected (first by the parliamentary party and then, if it gets to a two-horse contest, the wider membership), secures the confidence of the Commons and gets rubber-stamped by HM The Queen.

On Mrs May’s track record of promising to leave something, but not managing it, she’ll still be Tory leader in 2020 and, having fiddled all the rules to get some sort of extension, PM long after the next scheduled General Election. If that appalling state of affairs were to come about, though, she would no doubt insist that it was someone else’s fault. The EU’s fault. The ERG’s fault. The Remainers’ fault. The voters’ fault.

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None of that will wash. It’s all her fault. Mrs May is the most catastrophic prime minister since Lord North; probably worse. She had lots of room for manoeuvre, as he did not. That’s a harsh judgment, but it’s based on the terms she set, and which (unlike David Cameron) she was not pushed into, but herself chose. Her dreadfulness is not just a consequence of her own abject failures, but because she’s made things much more difficult for her successor than they would have been three years ago.

Some people think that this judgment is premature, because the next Prime Minister may be even worse. This accords with the narrative – popular with Remainers who think the public can’t be trusted with a say in their own governance, unless it conforms with the views of (sensible, liberal members of) the political classes – that Brexit was an impossible aspiration and any attempt to implement it was bound to be damaging.

On this analysis, the worse Mrs May’s successor fares, the more kindly history will judge her. When whichever of the 330 Tory MPs standing gets the job, and makes just as big a mess of it, we will see that she was dealt an impossible hand, and played it as well as she could.

I’m afraid that’s nonsense, too. In poker terms, she was dealt at worst a pair of sixes, and promptly swapped them for seven two offsuit. Those who complain about the lack of specifics in the Leave campaign, and a failure to spell out exactly how Brexit would be implemented, can’t also maintain that Mrs May had limited options when she emerged (without, unfortunately, any scrutiny of her patent unsuitability for the job) as Tory leader in 2016.

That would have been that moment at which any halfway capable person would have said: “I promise we will respect the result, but before we go any further, we should establish the terms on which we go, and each of the possibilities involves some trade-offs.”

Faced with the range of options with which we are now drearily familiar, from Canada +++ to WTO terms, she could have spelt out which might create (say) border problems in Northern Ireland, restrictions on taking greater control of our agricultural or fisheries, oblige us to continue to abide by EU regulations or ECJ oversight, prevent us from ending unrestricted freedom of movement, and so on.

We could even have had, for example, a series of indicative votes in Parliament to see which aspects of Brexit enjoyed enough support to make them worth negotiating for, which were regarded as essential, and which could be conceded in order to protect trade, industry or the financial sector. Did Mrs May even think about any of that? Apparently not.

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For the first nine months or so of her premiership, the only statement we got was “Brexit means Brexit”. Unless you’re a primary school teacher attempting to explain the reflexive property of the equals sign, this is of limited value in conveying information, even if we now know that the translation is: “I’m not telling you, because I have no idea what I’m doing.”

Worse, the fact that Mrs May didn’t know what she was doing didn’t stop her from preventing everyone else from pursuing the options. Her succession of Brexit secretaries, who all resigned because she wouldn’t let them do their jobs, may have been – as the Remain camp naturally claims – rubbish, or faced with the impossible. But we’ll never know, because they never got to negotiate.

Instead, at some point, the Prime Minister came up with new definition of Brexit. It was, apparently, a set of red lines. These, as it transpired, were akin to those the teacher puts through the wrong answer, or those used in alarming graphs showing that your approval rating is falling through the floor. And she was dishonest about the limits they created, and the (considerable) concessions that she immediately surrendered to Brussels.

In part, that’s because of the monomania about immigration she carried over from her time in the Home Office, which immediately ruled out most of the attractive methods of delivering Brexit. But the lessons of Mrs May’s previous job were not just that she was callous, authoritarian, stubborn, unreasonable and technocratic, though she was all of those. It’s that she didn’t even deliver; if immigration was her big thing, she failed for 10 years to do anything about it.

A better politician might even have sold her terrible Withdrawal Agreement (though I doubt it), but she’d already proved, in the worst election campaign ever conducted, that she was a terrible politician. Failing to gain a majority against Jeremy Corbyn, Labour’s worst and least popular leader ever, was seen, even as her campaign was collapsing almost comically, as an impossibility. Yet she managed it.

It’s perfectly possible, perhaps even likely, that the next Prime Minister will prove terrible at delivering a good Brexit, but that shouldn’t improve history’s view of Mrs May’s time in office. It’s her decisions, and hers alone, that have led us to this sorry pass. The only way forward is to acknowledge that every one of them was an error, disown them all, and start again.