The unlikely lad: Olly Murs on X Factor fame and the snipers who induced a bout of depression

He's got the number ones and the nationwide tour with Robbie Williams. He's got the TV gigs. And now he's go the dark back story. Can anything stop the irrepressible Olly Murs?

In preparation for meeting Olly Murs, I have been listening to him on Spotify every day for the past week. For such a new artist – he finished runner-up on the 2009 series of The X Factor – there's a ridiculous amount to listen to: three albums, 37 songs, assorted B-sides and live tracks.

As is the case whenever you listen to music while getting on with your working day, I don't always pay full attention to the songs, I never learn all the words or appreciate any subtle nuances, but after a while I find myself actually coming to like what I'm listening to. In truth, I wasn't expecting this, not at all, but his songs are perhaps the purest expression of pop right now: they are happy, catchy, and full of a boundless and thoroughly unpretentious enthusiasm it's difficult to resist.

His most recent album, last November's Right Place Right Time, is a frisky combination of Jamiroquai's radio-friendly funk and Maroon 5's incessantly high-tempo rhythms. This reads, on paper at least, like reason enough to run screaming to the hills – yet somehow it works. It's fun; throwaway definitely, yet unaccountably pleasing on the ear. But then, Murs on record is much as he is on television: a likeable, cheeky chappie, and ultimately difficult to sneer at no matter how predisposed you may be to sneering.

And now here he is, in the flesh, striding across the soft carpet of a VIP bar at London's Indigo2 venue where, later tonight, he will play a gig. He looks not unlike a waxwork version of himself, everything about him as you might expect: clad in a Fred Perry top so snug and buttoned up you fear for his Adam's apple, natty slacks, good shoes, a sideways smile on his disarmingly wide face, and a habitual twinkle in his Essex-boy eye.

"All right, mate?" he asks. His handshake is firm, and we relocate, in two swift strides, to a private booth where he starts to talk on automatic pilot, interviews being so much a part of his daily life now. His eyes wander the room as he talks, and much of what he says is the stuff of pop- star cliché, but it's clearly heartfelt, and he means it all the same. He has a way of talking that is pure wideboy caricature: out of the left side of his mouth, almost covertly, as if letting you in on a secret, or perhaps attempting to offload on to you some recently stolen goods.

This far into our complicated relationship with reality-TV singing competitions, we have developed certain requirements from, and demands of, those they serve up for our entertainment. Yes, we shall enjoy watching them succeed and flail every Saturday night, but we will then laugh at their cheek, their barefaced temerity, when they linger on afterwards expecting recording contracts, hit singles and blanket tabloid coverage. What the hell are they thinking? We will expect their hits to dry out quickly, their shelflife ending neatly with the arrival of another reality-TV singing competition that demands our all-too-fleeting affections.

Murs, however, seems to be one of the rare exceptions. He is still here, for starters, and ever-more ubiquitous, a pop star and TV presenter, his profile in the ascendant, any resistance we might have harboured increasingly futile. Coming second back in 2009 to the sweet, the doleful, the where-is-he-now Joe McElderry, Murs, with the help of firm record-company muscle behind him, quickly established himself as a fixture in the Top 10. Not for him the sudden, belated yearnings for singer-songwriterly credibility. Instead, he kept knocking out brashly commercial hit singles – number-one hit singles – and then albums. In 2010, his self-titled debut shifted more than 600,000 copies.

A year later, he released In Case You Didn't Know, which did even better. And then, late last year, he released Right Place Right Time, on course to be his most successful to date. He is about to head off on his biggest headlining tour, arenas all, and in the summer will support Robbie Williams on his Take the Crown stadium jaunt.

Give or take the occasional Will Young or Leona Lewis, this sustained success is a pronounced aberration for a reality-TV hopeful. But it can't be an accident, can it?

"I hope not," he says, grinning. "It's down to bloody hard work, if you ask me. I'm not sure people realise. When you see fame, famous people, on the telly and that, it all looks so easy… red carpets, falling out of clubs, girls. But in reality, it's hard work, relentless hard work, day and night. To get anywhere in this industry, you need to be a workaholic. That's what three years in this business has taught me."

Olly Murs is Essex born and bred. He is 28 years old, the son of a toolmaker and an HR consultant. He has a twin brother, Ben, and a younger sister, Fay. He was an OK student at school – though when he says to me, "If a song is wrote for me that sounds amazing, I'll do it," it rather suggests English wasn't his best subject.

From a young age, he admits, he loved the idea of becoming famous.

"Everyone does, don't they? I'd watch MTV, all these pop stars and their fabulous lives, and I'd say to myself, wouldn't it be great to be famous one day? It just looked like an amazing job."

But he didn't want to be famous merely for the sake of it. "No, I wanted to have a talent. I thought that talent would be football. For the life of me, I never thought it would be performing."

He was 23 when he accepted that a persistent leg injury meant he would never be able to pursue football professionally (he played semi-professionally for Witham Town), so he sought a replacement: singing. He started to do karaoke – a cheeky chappie, after all, only remains a cheeky chappie if he has an audience – and played gigs with friends in bands that seemed likely never to find an audience outside the M25. He tried out for The X Factor in both 2007 and 2008 before, in 2009, the producers finally gave him a chance to do his stuff on television.

His first performance on the show is worth watching again on YouTube. It's easy to be cynical about the programme now, to be resistant to how mercilessly it plays on our heartstrings, but much of the magic that made it so watchable in the first place still exists. Murs, dressed like a geezer on the pull, ambled on to stage, shy and wary but eager with it, to sing Stevie Wonder's "Superstition". He didn't have the best voice, and his dancing wasn't of a professional standard, but he radiated the kind of likeability that TV adores. At its conclusion, Simon Cowell did that thing with his face where his lips peel back to reveal more teeth than seem strictly necessary, and by the time he told Murs, "This is the easiest 'yes' I have ever given," the 25-year-old's life had already changed. He was instantaneously famous, instantaneously a winner.

"I couldn't believe it," he tells me now. "Still can't. You dream of it happening, sure, but you don't expect it. You'd be mad to."

To become a fully accepted public figure, however, there needs to be a little darkness to counterbalance all that shining light. In Murs' case, the darkness came on k the eve of the release of his debut album. During The X Factor's live finals, his twin brother Ben was preparing to get married. Because Olly was busy with the show, he missed the ceremony. They fell out, stopped speaking, and a year later Ben sold his story to the News of the World, referring to his brother as a "self-obsessed sell-out".

"That was a weird situation," Olly says now. "A private one that unfortunately became public. It had nothing to do with the show, not really. By that stage he wasn't talking to anybody in the family, not just me, and it was more to do with his relationship with his girlfriend… I don't want to go into too many details, but that's where it came from. There had been a lot of arguments. Basically, I think he just wanted to move on with his life, and then he did. But to not hear from him for that long, and then to see that he had sold a story, and taken money for it… Well, that was the hard part."

Will they ever reconcile? He shrugs. "I don't know. Hopefully, in years to come, when we are older and have families, then perhaps, maybe. We'll see. But it still feels like he was trying to jeopardise my career, selling the story when he did. That's hard to take."

And then, in the middle of last year, while he was touring his second album, hosting The X Factor spin-off The Xtra Factor and dating girls who, just two years before, wouldn't have given him the time of day, he started to change. Those closest to him noticed that he had become moody, defensive, and that, although never a big drinker, he was now starting to drink heavily.

"I was doing a lot of TV, not just Xtra Factor but popping up on things like [Channel 4 comedy panel show] 8 Out of 10 Cats. I just felt I had to drink myself to a point where I had that 'Olly Murs' personality again. Without it I didn't feel good enough, funny enough."

This subject was covered in his ghosted autobiography, Happy Days, which came out last year, and was subsequently reported by the media as a major depression. A cynic here might suggest that the story has been over-egged somewhat, perhaps to flesh out his character a bit more. He certainly talks about the episode now in a breezy manner one wouldn't automatically expect from someone blighted by depression. He tells me that it lasted "at least a couple of weeks". Nevertheless, it is clear that being catapulted to such sudden fame did come with side-effects.

"I was worried that doing the TV show would kill my music career," he says, having convinced himself that he would be overexposed, and also shown up for what he felt he was: an opportunist promoted way above his station. He has always prided himself, he tells me, on being a nice bloke, liked by everyone. "I've never walked into a room and been arrogant or confident [sic] or horrible to anyone. I've never belittled anyone. I've always been caring. And being seen like that – a nice bloke – was important to me. But now I was doing TV, and I was getting criticism every day – blogs, tweets, and you lot, the media. They hated me, I was a wanker, I was crap, I couldn't dress, I couldn't sing, I was rubbish on TV… Suddenly it seemed like nobody liked me. I didn't like that feeling. Didn't handle it well at all."

With hindsight, he decides, it probably wasn't depression, but more likely exhaustion, stress, a blip. And he soon bounced back. (His biography was not called Happy Days for nothing.) I ask him how he feels today, whether he sleeps well at night or is still dogged by a lurking paranoia.

"Oh, don't have trouble sleeping; never did," he beams. "I'm always out like a light."

I ask about his friendship with Robbie Williams. Williams had mentored him briefly on The X Factor, and the pair have remained close ever since. There are many reasons why Robbie Williams is such a compelling pop superstar, one being the way in which he wears his bruised heart so visibly on his sleeve. No matter how successful he gets, he remains perpetually sensitive, vulnerable, his skin thin. Is Olly similar in any way?

He looks confused for a while, and then says: "Robbie has always seen himself as the underdog, and I feel that way as well. He was never taken seriously because he came from a boy band. I'm not taken seriously – not properly seriously – because I came from a reality-TV show. He always fought against that, and so do I. He won, and I hope I will too."

Otherwise, they are not really similar at all, because unless he is concealing it particularly well, Murs is almost preposterously light-hearted, as carefree as a puppy. He knows how lucky he has been in life, and because he had to wait for it, because he didn't find fame until he was 25 – comparatively old in the pop game – he plans to nurture it. His fame, he seems to be saying, is like precious goods. Handle with care. It could break.

"Take tonight, for example," he says. "I'm doing this show here, there'll be some other bands around, a few footballers probably. I'm sure a lot of other people would say, 'Let's get the gig out of the way, and then have some drinks, get drunk. Yeah, we're working tomorrow, but sod it, who cares?'"

What he is trying to convey here is that he cares.

"Me, I'll go straight home, and to bed. I will. I've got work in the morning, you know? And tomorrow is another day. Got to keep focused, got to keep working at it. If I don't, who will?"

Olly Murs tours the UK from 2 March. For dates and more information: ollymurs.com