Steely desire driving on Lewis Hamilton

With a glowering, coiled intensity, Lewis Hamilton leaves no one in any doubt as to the scale of his ambition. "I ain't messing around," he says, laying a little extra emphasis upon his reincarnation in the silver and turquoise of Mercedes. For the Australian Grand Prix on Sunday signals nothing less than a renaissance for one of the most complex, misunderstood and polarising personalities that Formula One has yet bequeathed.

Win here at Albert Park, or so the theory goes, and Hamilton will be vin-dicated in his decision to forsake McLaren for an eye-watering pounds 60 million. Finish outside the top six, and his defection will be painted as a reckless move by a 28 year-old just as impulsive off the asphalt as he is on it.

The reality is nothing like so straightforward. Hamilton is switching teams not merely to try to seize his second world championship but to attain a degree of personal -freedom and fulfilment he felt was denied to him at Woking.

He describes the culture at Mercedes as "beautiful" and talks of being "in a good place". These are not meant to be knives thrown at McLaren but expressions of the imperative that he perceives in assuming a fresh challenge. "I'm absolutely loving it. I'm developing both as a person and a driver. I have so much that I still need to learn."

After four infuriating seasons failing to replicate his maiden world title in 2008, he relishes the sense of rejuvenation. He is working assiduously with Antti Vireula, his Finnish trainer, to help bring him to a peak of conditioning as he seeks to deny Sebastian Vettel a fourth consecutive championship. "I have bulked up. I have been lifting weights, more than ever before. Fortunately, because I am short, you don't have to be thin like a twig."

The liveliest debate before this F1 campaign is whether Hamilton's car, the sleek Mercedes W04, can help translate this optimism into results. Impressive winter testing times promise much, although he is mischievous about reining in the expectations. "We could just have been running lighter fuel than everyone else," he says, teasing.

Niki Lauda, Mercedes's non-executive chairman, has argued passionately that Hamilton - a McLaren product since the age of 13 - could enrich his reputation by delivering success at a different team. The prospect of emulating Lauda, winner two titles with Ferrari and another at McLaren, and even Michael Schumacher, who followed a double triumph at Benetton with five more for the Scuderia, is tantalising for him.

Hamilton is preoccupied deeply with the concept of greatness, talking earnestly of acquiring a Senna-like aura. He purports to demonstrate more maturity, claiming that he is content to wait for his elevation to such exalted company. "Inexperience led me to be impatient in the past But I am more patient now and I guess that comes with age."

Hamilton is almost universally identified in the paddock as the fastest driver in F1, brooking no compromise with his brand of aggression. Lauda describes him as "unbelievably quick". But the style has led to all manner of scrapes, including driving into the back of former McLaren team-mate Jenson Button in Canada in 2011 and tangling frequently with Ferrari's Felipe Massa.

Hamilton maintains that he has mellowed, that he will take the long view at Mercedes this season even if early races do not unfold as he would like. But he remains too temperamental a character to be taken fully at his word. To be in Melbourne this week is to be reminded of his infamous lapse here three years ago, when he was charged by police after being caught doing smoky burnouts and 'fishtailing' in a road car.

The wild side is the path most often travelled by Hamilton, who has just invested pounds 20 million in a private plane to ferry him about and painted it lurid red. Indeed, it is the most glaring contradiction in his character that he cleaves to his council-house background in Stevenage and yet flies on a private jet in bright scarlet. He argues that his favourite meal is some spicy chicken at Nando's but is equally happy indulging the Hollywood lifestyle with Nicole Scherzinger, the former Pussycat doll, in Los Angeles. Most controversially, he insists that he pays a "lot of tax", despite residing since 2007 in Switzerland and Monaco.

The counterbalance to such excesses is religion. A committed Catholic, Hamilton has described God being on his side behind the wheel and offered to say a prayer for Adrian Sutil, the estranged friend for whose assault trial he failed to turn up last year. But in Barcelona this month he became visibly irritated when asked to elaborate further on his faith.

The support of Scherzinger, his girlfriend of six years save for a brief split in 2011, has served as a calming influence, offsetting the family tensions that caused him to jettison father Anthony as his manager. Ensconced in the Mercedes cockpit here in Australian sunshine, he finds his sense of purpose restored. From his words as much as his lap times it is apparent that Hamilton does, indeed, mean business.