“It is possible that you are right and I am wrong,” David Davis writes to Theresa May in his resignation letter. The phrase was in a draft that I saw just over a month ago on the evening of June 6. Earlier in the day, he had been asked, after delivering a speech at RUSI, whether or not he would resign if the Prime Minister did not offer a date by which, in the event of a Brexit deal, the backstop arrangement over the UK-Ireland border would end. “That’s a question, I think, for the Prime Minister, to be honest,” he replied. This was less of an evasion than a confession. The Brexit Secretary was trying to think through, using the logic tree methods that he loves to deploy, what to do for the best – and what the range of outcomes of a resignation might be. He hadn’t made up his mind what to do.

The story of how I know so is as follows. The previous day, he had texted me: “are you around tomorrow evening”? This was unusual. I am a friend – having voted for him not only in the leadership election of 2005, but in the previous outing of 2001, shortly after being elected as an MP for the first time, and working briefly as his PPS. But messages of that kind don’t come every day. “Yes, if wanted,” I replied. “Which I seem to be.” “Dinner?” came the reply. “I could use some advice.” This is not a request I’d ever had from him before by text – or perhaps in any other form – and the terse terms expressed an unusual urgency. So it was that the next evening we found ourselves chewing his choices over, almost literally, over Albondigas and Pisto Madrileno upstairs at Goya’s in Pimlico.

Three main issues emerged. The first was the backstop. It was already known that he hadn’t been happy about its terms at the time when agreed, because he feared that, once the UK was in it, the EU might never let us out – thus trapping us in the Customs Union and Single Market, at least in part, in perpetuity. His conviction that the Government must find a route map to escape it, and that he might resign if one wasn’t forthcoming, wasn’t exactly a secret that day: his arrival at our small table was preceded by a frenzy of tweets from fellow political journalists speculating on what he had said at RUSI. He had sent me a text earlier: “Running late. On my way”. “Don’t resign before you arrrive,” I replied, to which the half-joshing answer came back: “nip and tuck, I reckon”.

The second issue was delay. Davis feared that if the Commons wasn’t presented with a detailed trade proposal in the autumn, it would vote the deal down, projecting the Government and the country into unknown and unknowable political territory. Hence the urgent need to get a move on: get a proper customs policy – the stand-off over agreeing one was helping to tick the clock down – get a broader approach agreed and a White Paper published; get back round the negotiating table. That he had spent only four hours since Christmas negotiating with Michel Barnier had been well reported. The bleeding obvious had gained less traction: that, until or unless the Government had first closed its divisions, there wasn’t much to talk about.

Which brings us to the third point. Someone had been regularly back and forth to Brussels on the Governent’s behalf, but it hadn’t been the man who Theresa May appointed to undertake the task: it had been Olly Robbins, her Europe adviser. Whatever one thinks of this decision, it may well be that, when the history of this Government is written, that the Prime Minister’s reliance on her adviser will be a pivotal part of the tale. Robbins was May’s Second Permanent Secretary at the Home Office. He was sent to DexEU as its first Permanent Secretary. He and Davis didn’t get on. So he was moved to Downing Street and his present role. The decision to use a civil servant as an emissary, rather than the politician appointed with an express brief for Brexit, has had consequences.

The long and short of it is that there was a feedback loop, in Davis’ view, between the wrong way of making decisions and what he saw as the consequence – namely, wrong decisions. He also claimed that the Prime Minister hadn’t been straight with him. This charge is set out in the resignation letter he sent yesterday evening, which refers to “the progressive dilution of what I thought was a firm Chequers agreement in February on right to diverge…the unnecessary delays of the start of the White Paper…the presentation of a backstop proposal that omitted the strict conditions that I requested and believed that we had agreed”. The implications of all this for others were infinitely more important than they were for me. But it may be worth mentioning that they pulled in different directions.

As a friend, I wanted Davis to flourish. As an editor, I wanted a story. As a Conservative, I wanted the best for the Government. As a Brexiteer, I wanted the best for Brexit – and, by extension, for my fellow citizens. Such were the conflicting pushes and tugs. For what it’s worth, I told him that if he really felt that he had to resign…well, then, he would have to resign. This doubtless wasn’t the most scintillating advice ever offered a politician, but for better or worse it was the best I could do. “Reckon it’s 50.50,” I tweeted afterwards. But I felt that the logic of the position leaned towards him quitting: if you can’t trust your boss, what other option do you have? At any rate, the decision went the other way. He had a long meeting with May the next day and, in short, decided to give her a second chance.

On the backstop, I felt he lost – that gaining a date by which the Government wanted a replacement was useless. More broadly, I thought he won. In those meetings, the Prime Minister agreed to get a move on with the White Paper and to set a date for a Chequers summit – which sets up an irony: Davis thereby gained the meeting that propelled his resignation. You will have noticed that he went dark over the weekend, in the aftermath of the Chequers agreement. I wrote on Saturday that he and four fellow Brexiteers, plus others in Cabinet up to a point, spoke out against what I call the Prime Minister’s new Brexit Minus Minus Minus proposal – which, whatever else may be said for it, isn’t the Canada Plus Plus Plus ideal which enthuses him.

He told me on Saturday that he was off to Silverstone yesterday (nice for some). He sounded dispirited. I asked him again if he would resign – it had become a staple opener to our conversation, rather as one might say: “great weather, don’t you think? – but, by now, the boy-who-cried-wolf factor had kicked in, at least for me. In retrospect, the warning sign was there: elliptical reserve was a better guide to the future than public agonising. And perhaps I had forgotten that he has a track record of quitting on principle. He said that he “might be busy” yesterday evening. “These resignation letters take a long time to write,” I replied – believing, wrongly, that one wouldn’t be forthcoming. “Well, I already have a work in progress…”, his text shot back. It was signed off with a smiley sporting a halo.

Saint to some, sinner to others: we will get both takes, and everything in between, today. Mamma mia! Here we go again. I repeat the most objective summary of which I’m capable. “There is no shortage of marmite politicians at Westminster, but Davis makes most of them taste like blancmagne. His friends’ take is that he is principled, brave, strategic, a deadly campaigner, highly intelligent, a lost leader, loyal to a fault…and occasionally exasperating. His enemies’ view is mostly unprintable. What can be written of it once the expletives are removed are such words and phrases as: egotistical, boastful, unreliable, opportunistic, a plotter, not a team player. There are quite a few of those friends and even more of these enemies – a fair number of whom are his fellow Tory MPs.

It may that the waters close over Davis with a quiet plop, that May appoints Michael Gove to replace him and sends Rory Stewart to Defra, and that life carries on much as before. This is doubtful, to put it mildly. Davis suggests in that resignation that the Prime Minister has been tricksy with him, and Downing Street will now feel obliged to trash his reputation – and with interest. As we have seen, it will not be short of an audience. More to the point, the cry is already up: who’s next? My successor in Wycombe, Steve Baker, has already gone. Like Davis, neither Boris Johnson, Liam Fox, Penny Mordaunt nor Esther McVey ventured into the studios this weekend to defend the policy that the Foreign Secretary has compared to a dollop of dung.

Will he “do a Heathrow”, as it’s known in the trade, today? But how can he now cling to office? And – as Mark Wallace asked last night, as he burnt the midnight candle – “bluntly, will May get the chance to appoint a replacement at all?” We are in full-parade-40-letters-bells-and-whistles-country. The 1922 Committee meets to be addressed by the Prime Minister this afternoon. These occasions usually star loyalists called early to praise the Party leader – after which those present warn of the dangers of a Corbyn Government (quite right too), denounce the media…and leave to brief their favourite journalists. This evening, it may be different – and not just in the sense that the meeting will be followed, with superlative timing, by the annual ConHome Parliamentary reception.

Like most of the rest of us, Davis likes to believe that his heart follows his head – all those logic trees; all that rational exposition – but sometimes, as for the rest of us too, it’s the other way round. “I don’t know how but I suddenly lose control / There’s a fire within my soul,” the song goes on. I have given the best account of what has happened that I can but, just as it is partial, it is also limited. There is sometimes a mystery to our decisions – a momentum that may suddenly drive them that we cannot fully explain. On the one hand, I am with my old friend. I think he was right to resign, and believe the new policy is a stinker. On the other, I believe that to hold a leadership contest now, with the Brexit negotiation still in place, would be narcissistic self-indulgence – not to mention an act of electoral self-harm.

It would be the greatest irony of all, would it not, were Davis’s resignation to kick-push a domino of effects which bring about the very opposite of what he wants: the collapse of the Government; the postponement of Article 50; the kicking of Brexit into the long grass – from which, buried deep, it never emerges? But what I think scarcely matters. Perhaps all that’s to be done is to follow the trail of what happens next. On Friday, a Government source warned “narcissistic leadership dominated Cabinet Ministers” to back the Prime Minister or “their spots will be taken by a talented new generation of MPs who will sweep them away”. We are about to find out whether or not that is true – and who will or won’t be swept away. One more thing, David: whatever you do, don’t call another bloody by-election.