Grand Prix legend Sir Jackie Stewart, as outspoken as always, is fearful that Lewis Hamilton’s off-track affiliations could blight his chances of a second world title.

The mental and physical fine-tuning of any Formula One driver is critical when they have to perform at their peak in a melee of fiercely committed rivals at 200-plus mph.

It is a perilous workplace, a distinct threat to life and limb, with no room for prima donnas or playboys and with the need for absolute commitment, but control, to counteract the talented opposition.

The job pays well, very well, and the salary providers quite rightly expect a fair return for their mind-blowing multi-million-dollar outlay.

And here Stewart, three times the champion with 27 wins from 99 grands prix, frets that Hamilton, newly switched from McLaren to Mercedes, could, as he has in the recent past, be deflected and distracted from his intent by the leisure-time company he keeps and his star-struck lifestyle.

It is peppered with rappers and showbiz luminaries, flights to the USA in his newly-bought private jet for Hollywood-style jollies with his glamorous girlfriend, pop singer and TV talent show judge Nicole Scherzinger, and a fall-out with strict disciplinarian Ron Dennis, his career-long mentor and guiding light.

There has been no indication from the 28-year-old that he intends to alter his ways, even though he vows complete dedication to the Mercedes cause for which, it is said, he is being paid £60m (Dh337 million) for a three-year tie-up. On top of that, he will reap the vast benefits of sponsorship deals.

The ink had barely dried on a cheque for £20m that Hamilton had signed to buy a jet for his worldwide commuting when Stewart’s concerned foreboding and a warning about his celebrity status and self-importance came into play.

The Scotsman, currently an ambassador for Team Lotus, was moved to hint at Hamilton’s threateningly self-destructive celebrity lifestyle with the comment: “If I had been Lewis I wouldn’t have left McLaren — but he is 28, a former champion, and he should know what he is doing.

“Now he needs to have more consistently good drives, never mind mechanical issues, and he shouldn’t be distracted — and that is something that he should keep in mind.

“It is all about who you hang around with, what you do with your time off and how you are committing your time towards your real time. And Lewis’s real time is being a racing driver. And he will have to deliver.”

Stewart feels that Hamilton’s saviour could be wise old head Ross Brawn, his new boss at Mercedes and the force, brains and astute guidance behind genius Michael Schumacher’s seven world titles at Benetton and then Ferrari.

And he urges Hamilton to ease off his hunger for fame and association with superstar celebrities. “He will have to work well with Ross Brawn, and depend on him, because he is a genius who knows how to do it and he can make Lewis a regular winner, maybe the champion, once more,” he said.

Brawn, by contrast, reckons Hamilton will be committed to a Mercedes rescue mission and says: “He will be the solution to get us to where we want to be. And he is relishing the challenge.”