Why? Let me take you back a little.

The first time I spoke to Bosse was at a press conference in 2014 on the eve of the IAAF Diamond League meeting in Monaco. In company with his compatriots Christophe Lemaitre and Pascal Martinot-Lagarde, he was wearing a sparkling hat, a multi-coloured garland and and puckish expression.

The mood was equally light as they looked ahead to their various competitions.

Despite his comical props (if athletes were Shakespearean characters, Bosse would always be in motley), the European under-23 champion was entirely serious as he looked ahead to racing the world record holder and Olympic champion David Rudisha.

“Why not be behind him, why not be the hunter?” he said. “He is not a god. He is beatable. It is not easy but we will see.”

As things turned out, Rudisha did prove beatable, but despite running what still stands as the French record, 1min 42.53sec, Bosse finished second behind the London 2012 silver medallist, Nijel Amos.

The Frenchman had also made it clear he was set on winning the European title in Zurich later that summer. He finished eighth.

Fast forward to 2016. At the European Championships in Amsterdam, there was more disappointment for Bosse as he came fifth. And the knife turned later that summer as he missed out on an Olympic medal in Rio by one place, going from second to fourth in the final 60m of a race that saw Rudisha retain his title.

This season began inauspiciously for Bosse as he struggled with a hamstring injury. Having had to miss the European Athletics Team Championships on the home soil of Lille in June, he arrived at last month’s IAAF Diamond League meeting in Paris desperately short of racing, but equally desperate to get some kind of a gauge on his form.

He spoke sombrely at the pre-race press conference of the peculiarly intense disappointment of finishing fourth at an Olympics, vowing suddenly: "Now I want gold. Nothing else.” 

Boom. That’s a quote. But to be honest, most journalists in the room were also thinking: “That’s a hostage to fortune.”

Bosse’s showing in the Stade Charlety the next day did little to alter that judgement as he went boldly for home but ran out of gas well before the line, fading to seventh in 1:45.71 – a season’s best. Time was not on his side.

But he retained his customary appetite for levity. At the previous year’s meeting in Paris, where he finished sixth, he had appeared for post-race questions holding a small grey cat.

The French athlete explained that his furry companion, Rabs, often gave him good advice before races. “This time, he asked me to take lots of fluids, which is what I did,” Bosse said. “However, he also forced me to eat Whiskas two hours before the race, and I hold that against him a bit as it wasn’t great.”

A year on, I felt the world needed to know if Rabs was still offering him bad advice and asked him for an update at the press conference.  As you can see for yourself here, Bosse picked up the ball and ran with it.

Although, concerningly, it appeared that Rabs had taken his coaching expertise elsewhere. “I didn’t see him for a long time,” Bosse reported with a grin. “So I have no news. I think he is around in the neighbourhood in Vincennes. If you should go there you should cross him maybe. I have no idea.”

The hat and the garland of 2014 may have been missing after his startling victory on Tuesday night, but the twinkling expression was unchanged as Bosse beguiled a series of interviewers with responses that ranged from unpredictable to alarming.

The Bosse Show had effectively begun when the camera came to him in lane 7 ahead of the final and he did a shorthand Marcel Marceau impression which was, as he later described it, a “bel hommage” to the King, Usain Bolt, following his shock 100m defeat.

So we got the "To The World" pose, followed by him rubbing imaginary tears from his eyes, pressing his palms together as if in prayer and then bowing with his hands down. It was all put together as perfectly as the race he was about to run – although as it later transpired, the race had been a matter of responding to the race with his emotions rather than running to a plan.

As he had in Paris, Bosse went for it around the final bend. But this time the field with race favourite Nijel Amos, the London 2012 silver medallist, could not catch him.

Shortly after crossing the line in 1:44.67, Bosse was nabbed by the infield MC, former European and Commonwealth 400m champion Iwan Thomas, and asked of him:  "I live a dream, I'm in a dream right now. Am I dreaming?"

Thomas responded in the negative, underlining to the dazed athlete alongside him that he could now call himself champion of the world.

"Trust me, I live my dream,” Bosse told the press a little later. “Or am I dreaming? Thanks to the crowd for the support. I still can't believe it.

"I am a gambler, I love going to the casino. And today I just gambled, I put everything on the red, even my last Euro. So hopefully, this is also for luck in love.

"I feel over the moon, I cannot describe my emotions.

"I did not have any race plan, believe me. I just did it with feeling. I came to London and I was not in a very good shape. This is the best thing ever. I surprised myself, I surprised everybody.

"I achieved this victory with a lot of determination, it was with my mind, not with my legs and not with strength.

“It felt like a nightmare as I was getting chased. It was a never ending nightmare. I could not understand why nobody was going past me. Even when I crossed the line I could not believe it.

"The others killed themselves and they were already dead in the last 100m. I was like a witch casting a spell on them.

"Finally today I was ahead of everyone. People can forgive me now because I now have that world title.”

Pierre-Ambroise – what’s to forgive?