Lewis Hamilton today took the wraps off the “elegant” new McLaren Formula One car he hopes will help him retain the world championship.

But there was a shock as his mentor Ron Dennis then revealed he was to stand down as McLaren's team principal.

Dennis had previously signalled he would scale back his involvement with Britain's most successful motor racing team but his announcement that he will hand over control to long-serving No2 Martin Whitmarsh on 1 March was a surprise.

The 61-year-old took charge of McLaren in 1981 and went on to steer the team to seven world constructors' championships and 10 drivers' titles. Some of the greatest names in post-war Grand Prix racing became champion under him including Niki Lauda, Alain Prost, the late Ayrton Senna and Mika Hakkinen.

But Dennis always regarded Hamilton, who he has guided up the motor racing ladder from junior karting to becoming, at 22, the youngest world champion, as one of his greatest successes.

Hamilton, who launched the new McLaren-Mercedes MP4‑24 at the team's Woking headquarters, said: “I will always remain close to Ron. I first met him when I was 10, we've got a great relationship and he has made a huge impact on my life. He still does today.

“But it's not as though we're going to struggle now. We've still got great people in the team. It is a huge team, and we're very powerful all together.”

Dennis intends to devote more time to overseeing the development of McLaren's new road-going sports car which is set to be launched in 2011.

He said: “I want to work harder in other areas, and having to plan those tasks around a Grand Prix calendar is sometimes disruptive to that process. I will still go to races, though not all of them, because I'm passionate about Formula One. But it is absolutely time for Martin to take over the job of team principal.

“It is a job Martin will really embrace and enjoy. It is a job that in practice we've shared, anyway. But now it is going to be his decisions that determines the outcome of certain things that take place at a Grand Prix circuit.”

Whitmarsh's principle task will be to keep Hamilton on track for a second title in a season in which all the teams are having to adapt to a raft of new regulations designed to make Formula One more exciting.

Hamilton is relishing defending his crown and said: “I feel more relaxed simply because I've come off a great season. It's like when you go race to race.

“If you've won the previous race then at the next one you have that little extra confidence.”