Interview: the thing about Sting… is that he is arrogant, stubborn, hypocritical and pretentious. Or is he? As he approaches his 60th birthday, Elizabeth Day joins him in France and discovers just how wrong you can be...

Sting is sitting on a bar stool in a white T-shirt and grey camouflage-patterned combat trousers, playing a harmonica. In front of him, a 20-piece orchestra is half-way through a classical arrangement of one of his songs, producing a swelling crescendo of sound that fills the stage. Behind him rise the steep, stone-hewn seats of a Roman amphitheatre in Lyon where, later tonight, Sting will play to a packed crowd of French fans as part of his Symphonicity world tour.

In the middle of the sound-check, he shakes his head and stops playing. The harmonica wheezes gently in protest. Everyone falls silent. Something is bothering him and no one is quite sure what. Will he throw a diva-esque tantrum à la Mariah Carey, and demand that his dressing room be re-stocked with lilies? Has someone forgotten to fulfil his rider request for eight dwarf strippers and a bowl of M&Ms (no blues)?

"That should be an F sharp," Sting says after a few seconds of tense silence, pointing at the clarinettist. There is a collective sigh of relief. The music resumes and, this time, the clarinettist gets his notes right. Sting looks over and gives him the thumbs-up. The clarinettist beams with pleasure.

It is, perhaps, precisely this attention to detail that has given Sting such staying power. His musical career has now spanned a quarter of a century and along the way he has scooped 16 Grammy awards, sold more than 100m records and written some of the most memorable songs of the past three decades ('Roxanne', 'Message in a Bottle', 'Englishman in New York'). By the time we meet, the Symphonicity tour, which features orchestral re-workings of his substantial back catalogue, has been playing to packed venues for the best part of 18 months.

It becomes clear, throughout the rehearsal, that the members of the orchestra both respect Sting's musical instinct and want to please him, as though he is a favoured teacher they are desperate to impress. Even the world-weary roadie next to me, who has spent most of his adult life on tour with various rock stars (Rod Stewart was, he confides, a nightmare) speaks about him like a mooning teenage girl. "Sting has such respect for other people," the roadie says. "He's just a great guy."

Oh please, I think to myself. He can't be that perfect. What about all those awful press articles you read about him? The ones with the yoga lessons, the constant preaching about saving the rainforest, the overly earnest attempts to paint himself as some kind of eco-warrior when his carbon footprint must be the size of Pluto? What about the rumours of arrogance and stubbornness, the fact that when the Police broke up in 1984 - one of the most successful British rock bands of all time - the drummer Stewart Copeland said that an on-going argument with Sting about what drum machine to use in a recording session was "the straw that broke the camel's back"?

What about the tantric sex with Trudie, the networking events they hold in their Tuscan villa for spiritual gurus and creative thinkers, the biodynamic vineyards and the fact they were responsible for introducing Madonna to Guy Ritchie at one of their glitzy celebrity parties and, by extension, for subjecting us to all those photographs of Madge in tweed caps and tracksuits?

What about the accusations of unabashed grandeur, the rambling country pile in Wiltshire, the penthouse in New York, the chef who supposedly had to travel 100 miles to make Trudie a bowl of soup? What about the time when Elvis Costello, of all people, once called Sting's music "appalling"?

But then, just as I am thinking of every single negative press cutting I have ever read about him, Sting walks across to introduce himself. He fixes his eyes on mine, touches my arm and says: "Are you who I think you are?" and the effect is totally disarming. Embarrassingly, I hear a giggle, then realise it is coming from me. It is hard to convey the impact of his sheer physical presence. He is not especially tall, but his body is powerful: thick-set and muscled, the veins in his neck sticking out like a wrestler's.

Later, of course, it will strike me that it was a particularly clever opening line, managing simultaneously to give the impression that he knew who I was without actually needing to remember my name. "I have to wash before I speak to you because I stink," he continues, his voice a weird transatlantic potpourri of vowels and dropped consonants. He smiles, blue eyes glinting, then walks briskly off stage. Everyone turns to watch him go

The roadie looks at me, raising his eyebrows. "Told you," he says, grinning.

After Sting has showered and changed into a T-shirt and combats that look exactly the same as the ones he was wearing before, we walk to a nearby café and sit on the open terrace, facing each other across a wooden picnic table. He is turning 60 in October (taking advantage of this milestone to release a 25-year retrospective box-set of CDs and DVDs) and so, to break the ice, I ask him if this makes him a Libra, believing that my feigned interest in astrology will doubtless appeal to his "spiritual" side.

"Well I'm actually an Asparagus," he says, deadpan. "Unique sign."

Then, after he has ordered a miso soup and a shredded vegetable salad with Tahini dressing from his personal chef, I ask him about his diet. Is he strict about what he eats? "Officially yes. Unofficially: it's ice cream, chocolate, wine." But doesn't Trudie tell you off? "No, no, no. I mean, she tells me I'm being silly when I'm being silly. When I have too much wine, it's 'Darling!' She's pretty disciplined."

Well, this is most unexpected. Five minutes in and Sting has already demolished the mung-bean-eating myth of himself as pop music's answer to the Dalai Lama. The next thing I'll find out is that he's fed-up of tantric sex… is he? "That story is 20 years old," he says, protesting. This is slightly disingenuous – in January, he and Trudie, his film-producer wife of 18 years and mother to four of his six children, gave a joint interview to Harper's Bazaar in which he claimed: "I don't think pedestrian sex is very interesting… we like tawdry." To which the near-universal response was: put it away, love.

"If you want to ask me seriously what tantric sex is, I might try and give you a coherent answer," Sting says now, sipping spoonfuls of miso soup. "It's using every aspect of your life – whether it's walking, breathing, eating, speaking, making love – as an act of devotion or an act of gratitude. That's all it is. The whole idea of seven hours of fuc – " he stops himself, "of intercourse – I mean, please!"

We laugh. In person, Sting seems to take himself much less seriously than the public image of him would have us believe. Given all the flak he has attracted over the years in the press, does he care what people think of him?

"In some ways I consider it an advantage to know how other people view you. You're under no illusions about how you're thought of. You have to strike a balance: there's people who can't stand the sight of you, there's people who really love you and obviously the truth is somewhere in the middle. That's the passage I'm navigating… I don't get unduly hurt. I might get a bit crazy…"

What – you might punch someone (the Police were well known for their impromptu back-stage fist-fights)? He gives a lazy smile. "No, I wouldn't do that. I might rehearse it in my mind, but I wouldn't do it."

He spears a sliver of carrot with his fork and chews, thoughtfully. The sky darkens and a few droplets of rain fall on the ground. Within minutes, we are in the grip of a thunderstorm and four separate minions have come to bring him an umbrella, stacking each one up against the side of the table. "Thank you," he says, every time someone brings him another, obviously worried lest he appear ungrateful. By the time the storm clears, he looks like a cloakroom attendant.

It is all a very long way from Wallsend, Newcastle, where Sting – born Gordon Sumner – grew up in a house "where literally the ship yard was at the end of the street – surreal!" His mother, Audrey, was a hairdresser and his father, Ernie, a milkman. As a boy, Gordon helped his father on the round, but secretly dreamed of being a musician, plucking away at home on an old Spanish guitar left behind by an uncle who had emigrated to Canada.

"My ambition initially was just to make a living as a musician," he says. "I thought that was a very honourable way to make a life, to pay the rent, put some food on the table."

His parents' marriage was an unhappy one and his mother eventually eloped with one of his father's co-workers. In his critically acclaimed 2003 autobiography, Broken Music (written without a ghost-writer), he describes Audrey as "always looking longingly away from home for her salvation".

As the eldest of four children, Gordon bore the brunt of much of the marital strife: "because my siblings were younger I was trying to protect them from what I knew and that was a big strain for me. I was basically the keeper of secrets." He grimaces. "Still am." He says that, at the age of seven, he was "detached, lonely and driven" and that his personality has barely changed since. "That's basically where I am now – detached, really detached."

And it is true that no matter how charming Sting can be, there is a definite sense that you only get so far with him and no further. It is not guardedness exactly - in fairness, he answers every question I put to him – but more a sense that you are speaking to him through a layer of glass; that he is more comfortable in his own company, with his own thoughts, than with having to explain them to anyone else. He strikes me as a loner who, by dint of his profession, finds himself spending a lot of time around other people, explaining things he would rather leave unsaid. "I'm not usually happy," he says, "but at the same time happiness can be thought of as a kind of bovine state - cows are happy; I'm curious."

After attending a Catholic grammar school, he got various jobs - at one point working in his local tax office – before becoming a primary-school teacher in a nearby mining town. In the evenings, he played in local jazz groups, earning the nickname "Sting" from a band leader after performing in a bee-like black-and-yellow striped jumper.

But it wasn't until the late 1970s, after years of gigging, that Sting got his big break. He moved to London with his then wife, the actress Frances Tomelty and their baby son, Joe, and met the drummer Stewart Copeland. They formed the Police along with guitarist Andy Summers. Their first album was released in 1978 and included the track "Roxanne", about a man who falls in love with a prostitute. Sting never looked back.

He spent seven years with the Police before calling time on the band and pursuing a highly successful solo career. Copeland and Summers allegedly never forgave him (although a 2008 reunion tour, which raked in £108m, must have helped ease the tension somewhat).

Whatever you think of his music - and there are oft-repeated accusations of creative unoriginality, the sense that his songs are little more than hyped-up elevator musack – it has enjoyed remarkable longevity. "I don't think there's very much original in what I do," he admits. "In pop music, there's no such thing as composition. We collate from pre-existing tropes and then the originality comes in the interpretation."

Given that he put in years of hard graft as a performer, Sting has understandably mixed feelings about the modern narrative of reality TV show fame. "I think the idea of going straight from school and then becoming a TV star is bizarre because it doesn't give you any perspective. You know, I held a job down, I paid a mortgage, paid my taxes, before any of this happened so it allowed me at least to keep a balanced view of what was happening to me. I really value those times when I struggled. You know, we were poor. So I don't envy kids who go straight from X Factor to record deals. It's a kind of dangerous trajectory. That's my opinion.

"People nowadays say, 'I want to be famous,' not: 'I want to be a musician. I want to be an actor.' The first thing on their minds is: 'I want to be famous.' You've got to be careful what you wish for." He gives a dry little chuckle.

Sting's path to success certainly came with its own ups and downs - his first marriage was an early casualty, put under strain by financial insecurity and endless touring. Of course it didn't help that Sting fell in love with a next-door neighbour while the couple were living in Bayswater, London. The neighbour's name was Trudie Styler and the first time he saw her, Sting thought she looked like "a damaged angel".

The subsequent messiness as his marriage buckled was, he says now, "a huge psychological event. My first marriage is the only thing I've ever failed at and I failed miserably." He still feels bad about it - is that because of some lingering Catholic guilt from his childhood?

He pauses. "I don't think it ever goes away, that feeling of conscience, but I think I have a conscience anyway… I don't regret my Catholic upbringing, but I really don't like certainty in spiritual matters. I find that very dangerous. You end up with massacres and you end up with 9/11. Certainty is wrong. Uncertainty is a much more sensible position."

Sting and Tomelty had another child, Fuchsia, but eventually divorced in 1984, and he went on to have four children with Trudie. Does he think he is a good father? "I wouldn't say I'm a good dad. You know, I'm a travelling musician rather than a dad. But I take my job seriously and when they need to talk to me or need a shoulder to cry on, I'm definitely there for them. And as they get older, their problems become more interesting. Young kids, I'm not that keen on, but as they get older you can actually talk to them, about relationships, about the meaning of life - now that's fun."

He admits that he "adores" being on the road. "I enjoy it. It keeps me out of trouble."

What sort of trouble would you get in otherwise? "Oh God knows. Crime…" he laughs. "I can't imagine life without working. I think one of my anxieties is the idea of doing nothing terrifies me. I love the feeling of forward momentum. It's become an addiction."

Does he think, in some ways, he is like his mother - always looking for stimulation outside the home? He ponders this. "It's very hard to stay in one place. But at the same time, I like somewhere to orbit. I like the fact there's a family home somewhere. Without that central point I think I'd go crazy, I'd spiral off into…" He leaves the thought unfinished. "My family have sort of learned to deal with it - they understand it's what Dad does. I get anxious being still. It's really a discipline to settle down." Is that why he took up yoga? "To calm me down?" He nods. "I think so."

Of course, the problem with this ceaseless wanderlust is that it does rather conflict with his stated desire to save the planet. When you combine it with the fact that Sting owns several glamorous homes in various countries and travels between them by aeroplane, you have to question how it is that he squares his carbon emissions with his 20-year-long campaign against deforestation (he and Trudie set up the Rainforest Foundation in 1989). Is he a hypocrite?

"Well that's the narrative: venal celebrities preaching to the world about climate change. The fact is none of us can help but do the wrong thing. I'm assuming you didn't come here on a donkey, right? Tomorrow, I'm going to get on a plane and go to another city and admittedly my carbon footprint is massive. At the same time, I say we shouldn't rip up the forest because if you read the Stern report, all of us could stop travelling tomorrow, industry could stop tomorrow, but the largest contribution to global warming is deforestation – by a huge, huge amount. So until we do that, we might as well just carry on."

The rain has stopped now. We sit and chat a bit more - about Hilary Mantel's Wolf Hall, which he recently read and loved, and about whether his phone has ever been hacked: "Probably. I'm sure Trudie's has." After a few minutes, he leaves to prepare for the evening's concert.

Later, sitting in the wings, watching Sting on stage, it is obvious that I'm in the presence of a consummate performer. He cajoles the crowd, teasing and flattering them in French. His voice expands to fill the amphitheatre. He flirts with the backing singer and the female conductor, without having to do much more than raise a judiciously timed eyebrow. He is in total command of the stage, the orchestra and the audience.

I begin to wonder whether the whole interview has simply been an extension of this performance, a further example of his ability to assume a persona in order to charm.

But then, after the show, he invites me to come back and join a few of the musicians at the hotel bar where he orders wine for everyone on his tab. He introduces me to Paul, a friend from Newcastle days whom he has known since he was 11. Paul is holidaying nearby with his wife and daughter and when Sting found out, he invited them to come and watch the gig. The friendship between the two of them is easy and affectionate and clearly genuine.

What was Sting like when he was 11, I ask Paul? "Exactly the same," he replies in a broad Geordie accent. "Exactly as he is now."

Sting: The Best of 25 Years double CD is released on 24 October

© The Observer by Elizabeth Day