The lady’s not for turning ... so is this the package May planned to deliver all along?

History will not remember Theresa May as one of Britain’s great prime ministers. Nor as one of its luckiest. But posterity might, just, afford her a place in the pantheon of most resilient leaders. Retrospect might even suggest she was more calculating than anyone suspected.

The Brexit deal set out in Brussels yesterday is testament to Mrs May’s extraordinary toughness, a willingness to endure public abuse, collegiate acrimony and private despair, yet not give up. Her predecessor may have run away from the scale of the Brexit challenge he gave Britain, but Mrs May has stayed at her post.

Whatever you think of it, whatever questions it leaves unanswered and whatever trouble it stores up for the future, remember this: many of those now passing comment on the deal were six months ago convinced that Mrs May would not be in office by now. Her capacity for pain and ability to survive apparently mortal wounds – including self-inflicted ones – are the foundations of this deal.

The greatest of those wounds, the botched election, is perhaps key. For when Mrs May lost her Commons majority, she made compromises on Brexit inevitable, since she (or any other Tory PM) would lack the votes – and authority – to drive through the hardest form of exit sought by purist Leavers. Looking back, it is hard not to wonder whether, within hours of the June 8 disaster, she had already calculated that only by making the subsequent negotiating process look unendurably hard might she be able to placate those purists during the inevitable climbdowns to come.

Anyone paying close attention to the election result or Mrs May’s words since would have picked up on her real intentions. Her pre-election claim that “no deal is better than a bad deal”, for example, vanished from her Brexit script. The truth is that, whatever the political window-dressing and charade, she’s been telling us this was where she would go for months now – even if some didn’t want to listen.

Mrs May made an explicit acknowledgement of this reality in Florence with a speech confirming she was willing to accept a transition period after Brexit, a potential role for the ECJ, and to pay billions in a divorce settlement, if that’s what was needed to start trade talks.

Colleagues lined up to take a shot at her. Mrs May, like a boxer on the ropes, absorbed the blows but did not hit back. Yet nor did she change course. Her offer to Brussels remained on the table, only more extensive.

Such tolerance may best be ascribed to a post-election decision to play the long game and suck up the punishment. If she had made such a decision, by December it was paying off. For who was it who really backed down? Why did MPS who once felt they could use Mrs May as a punching bag over Brexit fall meekly in line behind her compromises?

The answer was supplied on Sunday by Jeremy Hunt, the Health Secretary, whose influence is quietly growing beyond his department. He publicly warned Tory Leavers to back Mrs May because without her, there might be no Brexit. And so May’s calculation has become the Leavers’ calculation: collapsing her deal might collapse her administration, unleashing political chaos in which the Article 50 process might just be put on hold.

Still Mrs May had more to suffer. The election failure causing this week’s spectacle of a British prime minister seeming to dance first to the fiddled tune of the Irish Taoiseach and then to the flute of the DUP. Again she soaked up the humiliation and scorn.

Does the deal secure her in power for the foreseeable future? Does it resolve the big questions at the heart of Brexit? Will it unite the Tories around a single European position? No, no, and no. There will be more trouble ahead, more drama and more torment for Mrs May. She may yet succeed and she may yet fail. But the endurance – and calculation – she has shown in the last six miserable months surely suggest she will stick at the job of Brexit through whatever it throws at her next.