Boris Johnson deposed, turmoil in the markets triggered by Trussonomics, Sir Keir Starmer finds himself catapulted from the Labour leader who didn't have a chance to one who could win the next general election.
He was often seen amongst contemporaries as a Kinnock figure not a Blair. He was destined to be the leader of the opposition, the one who - faced with that Johnson 80-seat majority - could rehabilitate the Labour Party but could never take the crown.
Sir Keir genuinely believes he will be the country's next prime minister.
For a politician who likes to equivocate on this question, not a shred of doubt.
When I ended the interview asking him if he was our next PM, he didn't pause: "Yes."
'Hope has turned into belief'
"I never thought for a moment that it was impossible to get the Labour Party from where it landed in 2019 back into government," he said.
"Plenty of people when I became leader of the Labour Party said: 'Good luck, Keir'. Then behind their breath they said: 'But you'll never do it in one five-year stretch'.
"Here we are, two and a half years into my leadership, and a hope of a Labour government has turned into a belief of a Labour government.
"We've done a huge amount. We've done change in the Labour Party that took years last time we were in a situation like this, having changed the Labour Party.
"What I did yesterday and what I will do here on, is show what change we can make for the country."
Now, a serious government in waiting, and a would-be prime minister who insists he is the party of sound money.
Starmer sets out his fiscal rules
I asked him how his decision to maintain £20bn of Conservative tax cuts (the income tax cut to 19p and the reversal of the national insurance rise) sat with that.
He set out his fiscal rules - the chancellor will do the same on 23 November, if the markets can wait that long - telling me that Labour won't borrow for day-to-day spend and will only borrow to invest.
"We want the debt to reduce as a share of our GDP so that the rules that we will operate to," Sir Keir said.
"Obviously, I don't know the state of the economy when we inherit."
And that now the big unknown - what might the economy look like for the next government - be it Labour or the Tories?
What Sir Keir is promising, for now, is that every spending commitment Labour makes will be costed.
"I said to my shadow cabinet, if we're making an announcement like lost money, that I need to see the funding, and we've set that out very, very tough. I'll continue to do that."
But he also signalled that he was prepared to make tough choices should he be elected.
How Labour would shift tax burden
It would be an incoming government that could be confronted with the need to either raise taxes fairly steeply or cut taxes.
When I asked him what his choices were, he was pretty straight telling me that his Labour government would shift the burden away from working people and towards those people with assets.
"In relation to people who earn their income from stocks and shares and dividends, then yes, we are looking at what is a fair tax approach in relation to that will set it out," the Labour leader added.
"You know, I think there's a lot of thought that if you earn your income through wages, you paid a certain rate. But if you earn it through stocks and shares and dividends, you paid a different rate.
"That is something we need to look at."
A broad shift then from taxing income to taxing wealth, Sir Keir clear that he is not a prime minister who wants to tax working people if he can get the wealthier to pay more.
The question is whether we will see a much broader shift in British politics. As Sir Keir puts it, hope this week has transformed into belief.
And the turmoil in the markets ever since the Truss government announced their (non) budget, raise questions about whether that belief will be tested sooner rather than later.
But, for now, an election is two years out. He has everything to play for - and the Tories have it all to lose.