We've been told that Liam Fox reached his own conclusion, called the prime minister and said he realised that he couldn't go on.
However what I believe is that the Cabinet Secretary Sir Gus O'Donnell had concluded that Mr Fox's position was untenable, that the prime minister was willing to give the defence secretary time until that report came out but was not willing to give him the confidence or the support he would need to fight any critical report and to hold on to his job.
In short he went before he was - in all probability - pushed.
Now exactly whether that was said to him and exactly what happened in the conversation we don't know.
What is clear is that there's a warm letter from him to the prime minister and a warm letter back; I suspect that is as much to do with trying to save their blushes as anything else.
It seems to me clear that David Cameron had said to Mr Fox you've got time to prove you can get out of this and that I will not push you straight away. What he had not said is I'm backing you.
Furthermore what David Cameron needed if Liam Fox was to resign was for people to say it was inevitable.
Since this saga has played out over eight days, that is precisely what he's got.
Return not impossible
There will of course be people who deeply regret Liam Fox going. There will be people on the right of the Conservative party who see him as a cheerleader for Margaret Thatcher's brand of foreign and domestic policies who wish he could have stayed.
But there will be few I suspect who are able to accuse the prime minister of doing him in or be outraged that this has happened.
The wording of those letters clearly allows for the possibility that Liam Fox will return to government.
The prime minister is very careful to refer to Mr Fox and his wife as friends and to say that he wishes to carry on getting their advice.
I suspect the message that has gone between them is - you don't cause trouble now and, who knows, there may be a way back.