Louis Walsh, X Factor judge: 'I act the eejit. That's my role'

Ach, Louis Walsh. You know the one – lisping Irishman on The X Factor, cries easily, tells contestants "I really, really believe in you … you are the real thing", puts through terrible people (Wagner, anybody?), pronounces Wagner with a W, makes his acts sing rubbish songs, votes for acts if they're Irish, responsible for Jedward's infamy. You're never quite sure why he's there, but he always is.

Walsh walks into the London hotel in a Prada suit, pink shirt, looking smarter and stronger than X Factor Louis. He sits down, grabs a coffee, starts talking and doesn't stop. A whirlwind. "What music do you like?" he asks. "I love music." And before I know it he's raced through the history of soul music, glam rock, Roy Orbison's wife Barbara, Bowie's early appearances with Marc Bolan, and the conversion of Cat Stevens to Islam. Phew! Exhausting. "I'm a fan," he says with a huge grin. "I like music even though I'm working on X Factor." He laughs at the absurdity of it all.

At first I think he's trying to make a Louis-Walsh-Knows-His-Music point. Then I realise he's just a man obsessed. "What's the first album you bought?" The Slider, by T Rex, I say. "Ha! I've got that. Black and white cover. Great." Any second, I think he's going to suggest swapsies.

So how come Walsh, music junkie extraordinaire, ended up managing boybands? Ah, there lies a story, he says. For 20 years, he was an agent for lots of Irish rock bands. He organised tours, kept them going, and made sod all money. Then he went to see Take That. He thought he'd hate them, but he loved them. "And I thought, I'd like to do that. I had to make money." After that he managed Boyzone and Westlife ("Forty-four million records sold, 16 No 1s," he says, as if playing word association). Later came a partnership with Simon Cowell, then the offer to judge on Pop Stars: The Rivals. He'd never considered television before. "I was hardly chosen for my looks."

But enough about him. Back to music. Favourite musicians you've interviewed, he asks. I mention Sinead O'Connor. "There's a lovely bunch of people!" he says with giddy abandon. Walsh is fabulously bitchy and indiscreet. Who would have thought he was The X Factor's very own Dorothy Parker?

On Pop Stars: The Rivals, his band, Girls Aloud, beat Pete Waterman's boyband, One True Voice, in the final. "Pete was my hero at the time. He's never talked to me since." Has he seen him? "I believe he's alive! Is he in a home? Ha ha ha ha ha!" He looks at Sara, his friend and possibly the most honest publicist in the world. "You know he took it really badly, don't you?" he says.

After Girls Aloud won, Walsh won the right to manage them. In her autobiography, Cheryl Cole suggests he wasn't up to much, and only contacted them twice. Yes, he says, there were problems. "You want the real story? OK, I'm going to tell you. There was a girl in Ireland called Nadine Coyle, and I said, go for this show. She is an amazing vocalist. A real, real singer. So I pushed her in the band, and I said Nadine is the lead singer." From then on, there were problems. "I never worked with them very well 'cos they kind of scared me, the five girls together." Why? "Five girls! Five girls is a bit scary." And he does look terrified. "They were all a bit scary. Generally, girls don't like each other. That's the problem. I couldn't help them with their hair, makeup, all those things. And from the moment I said Nadine was the best singer, the others alienated me." Not surprising, I say. "Well, she is the best singer! By a mile. But she didn't marry a footballer. If she'd married a footballer she'd have been a big star."

Cole went on to be a judge alongside Walsh in X Factor. Was there still tension? "Yes. Cheryl knows how to work it. Cheryl is all about Cheryl."

There have been rumours she will return to the show as a replacement for Tulisa, whom Walsh adores. So what if it's a choice between Cheryl and Tulisa? "Tulisa," he says without a beat. "She works hard; she's honest. I did say she's a chav in a tracksuit, but she's a good chav in a good tracksuit." He looks at me, defensively. "She's a lovely girl." I know, I say. "OK, I thought you were going to slag her off. I'm always getting ready to defend her. We bonded from day one. I was dreading meeting her. I thought she was going to be a right little knacker. You know, a real toughie." Who would he less like to meet on a dark night in an alley, Tulisa or Cheryl? "Oh Cheryl."

I tell Walsh I'm surprised by him. What d'you mean, he asks. Well, I just expected him to be … wetter. Ah, that's the TV, he says. "It's because I'm Irish and act the eejit. But that's my role on the show. I act like I'm a bit stupid." He loves Ireland, says the Irish are the best people in the world, and splits his time between Dublin, Miami and London, where he stays in this hotel.

Walsh finds it hard to explain how he's different from the TV Louis. It's more than playing the eejit, he says, and looks at Sara. "Sara. Help me. Sara Lee knows me really well. I take my job very seriously on the show."

"He's much more serious on the show," Sara says. "There have been years he's taken it so seriously I have worried about his health."

"Well, you know why," Walsh says to both us. "Because the acts are depending on me to get them through. It's life or death to them."

Although Cowell is now giving his time to X Factor USA, Walsh still thinks of them as a double act. "When I'm with Simon we always laugh. I'm very like Simon. We're in this business of selling music and selling dreams. But people don't realise he's actually brilliant fun. He's so much nicer than people think he is. He never curses, is never rude to people. Ever." He clarifies. "Off camera, that is. People think he's this tough, ruthless, money-making machine. I don't think he loves money that much." Who likes money more? He thinks about it. "I'd say me … because I don't have as much as him." How much is he worth? "Enough. I like to be able to buy things. I buy a lot of art. I buy Andy Warhols."

"He has the most amazing art collection," Sara says.

Like who? "Hirst, Hockney, Herring. That's just the Hs." He grins.

Does he have to do everything Cowell says? To an extent, he says. Take his hair. "Simon said, 'Darling you're losing your hair,' and I said, 'Darling, I'm not.' Then he showed it to me on camera and I was. He said, 'Darling, you should get your hair done.' Everything is 'darling' with Simon. So I said, 'OK darling, I'll get it done.'"

How much did it cost? "I don't know. I didn't pay for it. That's why I'm telling everybody I got it done. That was the deal!" He invites me to have a touch. "See, it's all real," he says proudly.

You're looking good for 60.

"I know. I know!"

He looks different from when he was first on telly. Has he had plastic surgery?

"No, and I've never done the gym in my life. I'm a fat fuck."

"You're smaller than you were," Sara says. "Last year was a big weight loss."

"Oh, my eyes!" Walsh shouts, as if he's just remembered. "I've had my eyes done. No Botox. But I had my bags taken away about three years ago. Sharon Osborne, my good friend, sent me to her doctor to have my eyes done in LA, and it made me look 10 years younger."

Has Simon had much work done? "That's his own hair. But I'd say everything else has been done. He's very vain, and he's looking younger." He giggles. That's all I'm saying."

This year's X Factor has been disappointing. I tell him my kids – a reliable X Factor barometer – are bored with it.

"I think the press are trying to slag it. It's like the Manchester United of TV programmes. Everybody wants to slag it off, but they're still watching it. We're still doing 20 million people in a weekend." Aren't the figures falling? "A little bit. But nothing much." Isn't Strictly Come Dancing beating you? "No, I don't think so … I honestly don't think so. No."

Sara gives him a look. "Well, figures-wise, it is," she says.

The problem, I say, is the judges – they are dull.

"No," he protests. "No, we're really getting on. There's a really good chemistry between us. There's no tension."

Perhaps that's the problem, I say.

Sara nods. "I think Simon has a point. There isn't enough tension this year."

"We're probably missing Simon Cowell, and maybe Sharon Osborne," Walsh concedes. Would he bring them back? "I'm all for that."

So you'd dump Gary Barlow? "Well, he has a lot of work to do. He has a tour to do." And Nicole Scherzinger? He shrugs happily. "It's nothing to do with me."

But you wouldn't want to get rid of Tulisa? "No, no. You need two girls. You could have Tulisa and Sharon."

Walsh is open about everything but his private life. It's not that he's uptight about it, there's just something rather old-fashioned about him. I ask if he's gay. Ach, who cares, he says. "My sexuality is irrelevant. Next question."

I ask how it affected him when he was falsely accused of molesting 25-year-old Leonard Watters last year in a toilet. Within seconds the giddy, giggly Walsh is almost in tears. In January, Watters was jailed after pleading guilty to filing false reports to the police, and Walsh is suing the Irish Sun. "People knew it was untrue, but they still put it on the front page. They tried to ruin me. They are just vile people. Nasty people. The funny thing is they have an anti-bullying campaign in the Irish Sun at the moment. It's the most ironic thing."

His eyes are red, and he looks at Sara. "You know the real story. It ruined me. I'll never get over it, I'll be quite honest with you. I'm wary of everyone now, of everything I say, everyone I meet, always looking over my shoulder – I was never like this before. It was the worst thing that happened to me. All I have in this business is my name, and I would have lost everything. People would have said there's no smoke without fire."

Is it true he was suicidal after the story emerged? "I thought people wouldn't believe me. How can I go home? My family in Mayo. I thought about it. I had the sleeping tablets. I have to be honest, Sara got me through it that night." How? He laughs. "We had to sleep together."

She corrects him. "We stayed in a bed together."

"We were in a room up here together for 24 hours," Walsh says. "I was in this daze. By the way, the guy's in jail now. I hope he's reading this in jail. The fact that somebody set out out to destroy me is a real strange thing to deal with. I've blocked this whole thing out of my mind. I hate talking about it."

Anyway, he says, enough misery, let's talk more music. He tells me how Bowie is still his hero, gossips about who's sleeping with who in pop, talks about the fox in his back garden who is a dead ringer for Ed Sheeran, and says somehow they've got to find a way of stopping melodramatic Christopher Maloney from winning X Factor. ("The other contestants call him shake and fake. He keeps getting really big votes, though.")

A while ago Walsh suggested he would retire in his mid-50s. What happened? The grin's back on his face. Well, he says, how was he to know how things would work out? "Why would I retire now? I'm having a great time."