Rishi Sunak was sitting surrounded by television cameras and blissfully unaware of the painful political storm which would soon hit.
Late on Thursday afternoon in London, the prime minister had already committed what would come to be seen as an enormous error of political judgement. But he and his Number 10 advisers had yet to even spot it.
The error seems to have been two-fold.
Firstly, the decision made many weeks back – before the general election was called – that the prime minister could miss a major part of the 6 June D-Day commemorations.
And secondly, never revisiting that decision once the election had been called and considering how bad it might look.
One Conservative source has told the BBC it just did not occur to anyone at the top of the campaign that it would be a problem, especially with the G7 summit in Italy next week where the prime minister will see all the same leaders.
Mr Sunak took part in an interview with ITV when he returned to London on Thursday afternoon – but I am told the details of that encounter had only been finalised the day before.
I understand that ITV had asked for an interview later in the week, but were offered Thursday as the only option by Downing Street.
This means the decision to leave Normandy before the international leaders event was not made specifically to do a TV interview but to do other work.
Even as the interview with ITV’s Paul Brand concluded there was no sign the prime minister was regretting his travel plans.
Longstanding security concerns mean Number 10 are always cagey about the prime minister’s movements. Therefore, the fact an ITV interview was even being conducted was not widely known at Westminster.
Because it was being pre-recorded for a programme next Wednesday, the link to the D-Day anniversary may never have come to light.
However, an ongoing row between Mr Sunak and Sir Keir Starmer over tax policy meant this interview was the first time the PM responded on camera to accusations of “lying”.
That particular answer was clearly time-sensitive in the midst of an election campaign and the broadcaster decided to use the clip immediately.
At 8.45pm on Thursday, Paul Brand tweeted a of Mr Sunak’s answer on tax policy.
Within 10 minutes political journalists had made the link between the two events and were asking the Conservative press office when the interview had taken place.
Official Tory sources were almost all silent.
By 10.30pm, the Labour-supporting Daily Mirror had released its Friday front page: “PM ditches D-Day”.
As anger among Tory candidates grew, aides to the prime minister debated how to respond.
Their conclusion was to apologise fast and at 7.45am today Rishi Sunak tweeted: “On reflection, it was a mistake not to stay in France longer – and I apologise”.
Among allies of Mr Sunak there is bafflement about how another campaign blunder came about.
“From one decision to the next I’m absolutely staggered,” one cabinet minister told me. “Who is in charge?”
Another source who knows the Downing Street team well said of Mr Sunak: “He surrounds himself with yes men and women who don’t challenge him.
“They are all young. None of them have run a campaign before aside from Isaac [Leo]”, the party’s campaign manager.
Others involved are more sympathetic to the pace and pressure of being on a party political campaign far behind in the polls: “Someone dropped the ball and didn’t realise it.
“They are in the midst of a stressful election, grappling with problems on all fronts. It’s easy to say now that it was an obvious error.”
One senior Conservative told the BBC: “This is catastrophic. Reform will overtake us now [in opinion polls] and we will go into meltdown.”
Some Conservative candidates are seething, others seem deflated and resigned.
“We are where we are”, one critic of the PM told me. “I did try to warn them [about Mr Sunak].”
The potency of this gaffe is in its simplicity.
Unlike many political rows which involve complex procedure or political figures you’ve never heard of, all voters can understand this story.
As well as prompting questions about the PM‘s judgement, critics will say it jars with his plan to introduce national service and present the Conservatives as the only party that can be trusted with national security.
And like many of the most painful political errors, it was completely self-inflicted.
