Mark Webber is a jeans and t-shirt sort of man. So what was he doing in Dougie Hayward’s Mayfair tailors?

His friend Sir Jackie Stewart had arranged the visits to the shop on Mount Street because he thought the down-to-earth Australian could do with smartening up.

That was not Webber’s style then. And it is not Webber’s style now.

Mark Webber clinched the World Endurance Championships with Porsche on Saturday in his new career

Webber speaks with David Coulthard in the paddock before qualifying for the Abu Dhabi GP in November 2014

What you see is what you get with him. He is wearing jeans, naturally, when we meet. He is speaking his mind.

His honest, straight-dealing style was shaped in a close and happy family upbringing. It was then conditioned by his fight all the way from the bottom of the world – Queanbeyan in the Southern Tablelands of New South Wales, Australia, to be exact – to forge a successful European motor-racing career.

Being 6ft 1in was another disadvantage, but succoured by his long-time partner Ann Neale, he started 215 grands prix, won nine of them, had 13 poles and 42 podium finishes, and in 2010 came desperately close to being Formula One world champion.

And this weekend, aged 39, he won his first global title: the World Endurance Championships with Porsche.

Sir Jackie Stewart fet the need to give Webber fashion nadvice in the hope he would dispense with T-shirts

The 39-year-old Australian's honest, straight-dealing style was shaped in a close and happy family upbringing

Webber wants to see a reduction in grid penalites

Speaking to Sportsmail before he accomplished the feat, Webber blows his lips in something approaching exasperation when we turn to aspects of Formula One as they are today.

‘People talk about the mid-2000s or the Nineties and say they were boring,’ he says, rattling out the words at a 0-60 speed that threatens the record books. ‘They say there was no overtaking. But if you look at the grandstands they were full. Look at the TV figures. Why were all those people watching then and not so many now?

‘I don’t know all the answers. But let’s try to understand them. It’s an accumulation of things.

‘Penalties!’ He lets out a big sigh, referring to the absurd grid penalties that have been handed out for engine changes, distorting the field. ‘Whatever. Who cares? Honestly, it’s farcical.’

Next on his hit-list is radio communication between driver and pit wall. ‘Keep pushing this back,’ he says. ‘People do not want to hear Roger Federer being coached on every point. It’s between Novak and Roger, in tennis. Or Lewis and Fernando or Seb in Formula One. Sort it out.

‘It is a technical sport, but we do not need to ram this down people’s throats. It’s almost that the audience are being over-educated about what is happening. They are given too much to consume.

‘In the World Endurance Championships, we see cars side by side. Bang, bang, bang. Yes, there are loads of different tyre compounds, but does anybody care? No. They are racing each other. Awesome.

‘The driver has to be the superstar. It is all about finding those gladiatorial components.

‘How do you make it more human? MotoGP is a fantastic example – you can see the guys physically doing their trade.

‘The other thing we need is Formula One cars to be like nothing else. Which they are not: they have never been closer to GP2 cars and sports cars in terms of performance.

It needs to be an exceptional experience to watch, and drive. The cars need to be fast in the corners, not just on the straights, where if you are going 190mph or 210mph, who cares? But what about overtaking? He now has his foot right on the floor.

Webber finished his Formula One career with nine wins, forty-two podiums and thirteen pole positions

Webber has not been afraid to give his opinions

‘If you want that, watch a go-kart race. It’s like Real Madrid v Manchester United, 13-12. Would that be right? Probably not. You can have a cracking match at one-all. Cracking, mate, cracking.’

Webber was a popular member of the paddock during his 12 seasons in Formula One. Part of that was due to his candour. When a Sunday newspaper ran pictures of Max Mosley, the then FIA president, in a sado-masochistic sex orgy, he disobeyed his Red Bull team to offer critical comments.

During the controversy over whether Formula One should be in Bahrain while there was civil unrest in the country, he was the lone driver to offer a view.

‘I was a man of 30 whatever, why should I not have been allowed to say what I wanted?’ he reasons.

This brings us to today’s drivers. He is not critical of them; only of the stultifying structure that hems them in.

‘All the personalities are in there, mate,’ he says. ‘It’s just that the commercial and marketing teams hide them. There are too many other factors for drivers to be asked about – tyres, drive-throughs, why DRS didn’t work. They switch off.

‘In football, or golf, or tennis, the top players answer question about their own performances.

‘In Formula One drivers have to be like mini-politicians. There is too much baggage. It is hard for them to get over their human side.

‘One of my first memories is watching Senna carrying his national flag in the car after he won. That’s banned now. It would be beautiful to see Lewis (Hamilton) holding the British flag.’

Webber believes Lewis Hamilton is part of the new wave of racing drivers that have to act like mini-politicians

Speaking of whom, Hamilton, with bling up to his earlobes, is the prime example of a driver who has managed to wriggle free of Formula One’s shackles.

‘He is not how I would do things,’ says Webber, crossing his arms across his chest, ‘but he is a good brand, absolutely. Is he penetrating a phenomenal market in North America? Yes. There is nothing wrong with that. Mr Beckham did that quite successfully.

‘Lewis is still learning about himself. He is unrecognisable from 10 years ago, but then we all go our own ways as we grow older. He is out there between races. He is not under a rock.

‘He parachutes in from LA to race in Spa. Does he look out of place? Maybe. His style might be a bit brash for the Europeans. But why should he change? He is how he is; I am how I am.

Webber refused to reveal who he would prefer to work with out of Hamilton and Sebastian Vettel in future

‘The thing up at Wimbledon,’ when Hamilton was turned away from the Royal Box for wearing a floral shirt rather than jacket and tie, ‘was that intentional? Was it a tactic? It disappointed a lot of people but it sort of worked because everyone was talking about it.

‘He is on fire in the cockpit. Absolutely on fire. He is phenomenally quick – that’s his big weapon. It is not the tactical, Germanic style of Michael (Schumacher) or Seb (Vettel); it is just lap time. He has feel, balance, is good in all conditions and pretty versatile.’

So who would he chose to race for him if he ever returned, as he says he might one day, to help a team: Hamilton or Vettel? He blows out his cheeks, again.

Webber in action with Jaguar in the Formula One testing at the Circuit de Catalunya on January 22, 2000

‘Lewis in terms of marketing and pace,’ he says. ‘Seb in terms of tactics and developing the car.’

Although he will not be drawn one way or the other, he seems to be generous towards Vettel despite their often fractious relationship during five seasons together at Red Bull. Webber felt the team, under the influence of the company’ s motor sport adviser Helmut Marko, was favouring the German, who was the product of Marko’s young driver programme.

Marko briefed against Webber when the two drivers crashed in Turkey in 2010, confounding the view of most neutral observers, who placed the majority of the blame on Vettel.

Relations within the team deteriorated until Webber retired at the end of the 2013 season. But, we are happy to report, that the two team-mates met at Monaco in May and talked over their differences.

Red Bull Racing Motorsport Consultant Helmut Marko (right) was believed to have favoured Sebastian Vettel

How do he and Vettel get on now? ‘Good, very good,’ says Webber. ‘I am happy about that. That was important for me. There is nobody I raced with that I haven’t got a good relationship with.

‘It is incredible how we were in each other’s lives in depth for a while. We were toing and froing in the championship for part of the time, though he got the lion’s share in the end. We had a chat last year and again this summer, and it sorted.’

And Marko? ‘We never had a relationship, so it makes no difference.’

And Christian Horner, the team principal, with whom Webber was once friends? Well, Webber’s contempt is encapsulated by one sentence in his new autobiography, Aussie Grit, when he says: ‘Initially Christian did well to keep his feet firmly on the ground as he started to mix in supposedly higher circles, but inevitably you could see him being seduced by the trappings of an F1 lifestyle.’

Webber believes Horner played one side off against the other in the internal squabbling. Are he and Horner reconciled? ‘He seems pretty busy at the moment, so we’ll leave him to it,’ says Webber. ‘We are both big enough and ugly enough to move on. We are all sleeping at night.’

Webber was not surprised when Red Bull Team principal Christian Horner was 'seduced by the F1 lifestyle'

Webber has never limited his interest to Formula One, or indeed motor racing. He is an avid follower of tennis – a big admirer of Andy Murray’s fighting qualities and a critic of fellow Australian Nick Kyrgios’s loudmouth outbursts ‘before he has enough runs on the board’. Another friend is Steve Waugh, the former Australian cricket captain and a ‘gutsy bugger’.

One fallen hero is Lance Armstrong. After the Texan wrote his book, It’s Not About The Bike, telling in aching detail of his fight against testicular cancer, Webber was so absorbed by the story that he travelled to the Indiana University Medical Center to see the nurse who cared for Armstrong and of whom the Tour de France’s most infamous figure said: ‘This is what an angel looks like.’ She was called Latrice Haney, and she, Webber and Ann kept in touch for years afterwards.

Cycling is one of Webber’s passions, so much so that he started the Mark Webber Challenge in Tasmania, a tortuous test of fitness, during which he once broke his leg in an accident that may have ended the Formula One careers of less hardy souls.

Webber was so absorbed by Lance Armstrong's book It's Not About The Bike he visited the cyclists's nurse

Webber and Armstrong passed each other by chance on their mountain bikes in America recently. There was no friendly banter between two former pals. A caption in the book that accompanies a picture of them training together in happier times reads: ‘Riding with the lie.’

‘Keeping the momentum in motor sport by going into World Endurance to work with a team and company like Porsche has helped me,’ says Webber. ‘It’s hard mentally to give up the adrenaline drug of testing yourself. That’s the challenge. It’s about feet out of bed in the morning – what the f*** am I going to do?’

Webber, who lives in Aston Clinton, Bucks, with Ann and their dogs, Simba and Shadow, is content.

He concludes: ‘Could we have done some things better? Probably.

‘Could we have made different decisions? Yes.

‘Could we have tried harder to get where we wanted to be? No way.’

Many Formula One biographies are dull. This one, already a best-seller in Australia, isn’t.