Norbert Haug, a former Mercedes F1 boss, says it's a "mystery" why Lewis Hamilton decided to jump ship to Ferrari for 2025.

On Monday at the Aston Martin launch, former Ferrari driver Fernando Alonso poked fun at Hamilton's reasoning - that it had always been the 39-year-old's "childhood dream" to race in red.

"It was not his childhood dream 12 months ago, no?" the Spaniard smiled. "Or two months ago, I guess. It was a different dream."

Indeed, Haug admitted that no F1 insider was more surprised than himself when he heard the bombshell news that Hamilton would leave Mercedes late this year.

"If I had bet on one thing, on a partnership in Formula 1 that would last forever, it would have been Lewis Hamilton and Mercedes," the German marque's former head of motorsport, Haug, told motorsport-magazin.com.

"I was completely blown away by it," the 71-year-old added. "I would have sworn that it would stay that way forever. And that he would stay after he was finished driving as a brand ambassador or whatever."

Toto Wolff, Brackley based Mercedes' team boss and co-owner, has not opened up on what went wrong between him and the seven time world champion beyond Hamilton simply explaining that he wanted a new challenge.

Haug thinks the real reasons are still hidden.

"It's a mystery," said the German. Very few people probably know that. Toto Wolff will know."

What is clear to Haug is that Wolff is saying goodbye to more than just a world-class driver, but also a global superstar. Wolff himself openly admits that he understands that Hamilton's departure might even have financial consequences for Mercedes.

"Are there any risks?" Wolff told CNBC. "Of course, because Lewis is much more than just a driver. It is clear that after 2024 we will be missing something.

"But a team like Mercedes must have its own identity, and we will always have that in the future."

However, it might be argued that Ferrari is also taking a risk by welcoming what will be a 40-year-old driver to Maranello for 2025 and beyond.

"It takes a lot more effort at 40 than at 20," Haug admits. "But there are many drivers in F1 who are physically fitter at 30 than they were at 20 because they recognise the need and know how to feed themselves." body check tags ::