10/09/2012 06:53 BST | Updated 10/11/2012 05:12 GMT

INTERVIEW: Julio Iglesias On His Champion Son Enrique, What Dolly Parton Taught Him, And The Enduring Passion

"With Enrique, it's not a question of singing, it's a question of aptitude. He has the blood, the spirit, the character of a champion. you go into a fight with Enrique boxing, he'd kill you.

"The champions are the people who dictate the curves of the road, and it's very difficult to follow them. They go up to their limits and they became champions, and he is one of these."

Julio Iglesias with his sons Enrique (right) and Julio Jose in Hawaii

This would be an unusual description by a father of a son, except it's Julio Iglesias talking about his pop-star son, so instead it just sounds poetic, deeply wise and, of course, persuasive, in his suspiciously strong Spanish tones. (I guess I should have been prepared really for one of the world's most enduring romantic crooners to be deeply charming in conversation, but there you go...)

And the thing is, he probably does know what he's talking about. Julio Iglesias, along with a handful of others, has counted them in and counted them back out when it comes to musical artists stamping their mark on pop culture. While sounds, oeuvres, genres take their turn in the public consciousness, and contemporaries test their credibility at Eurovision - "I say to my great friend Engelbert, 'why you got to Eurovision? It's for kids'" - Iglesias just keeps on going with tours, high-profile events and albums, the latest of which is Numero Uno, a collection of his greatest hits, re-recorded, and of course an album that has already gone platinum in the Spanish-speaking countries where he has an adoration plinth all of his own...

Julio Iglesias - 45 years of music, and no sign of stopping...

It must be getting harder, surely? Iglesias agrees, but says not just for him...

"Before we'd be performing in a little club, there was time to learn, get it right, and if you got to number one, you'd be there for five or six weeks, it gave you time to learn. These days, you're number one only for a day, and if you're not number one, forget it.

"You have to be the best in the first session, and a lot of people aren't. Imagine being on the first day of something like Idol - very difficult - even for somebody like Paul McCartney, one day and it could all be over."

"I'm not Lady Gaga"

Fortunately, Iglesias is not competing with the likes of Idol contestants, but it seems there is a challenger closer to home...

"I used to play football for Real Madrid, and to be on stage for two hours, I can tell you it takes the same amount of strength. I will have the voice until I die. I just don't know if I will have the body. It is more difficult now."

I bet it is. And with so many dollars already in the bank, 300 million records sold, what still gets him up there night after night?

"When you give, you receive. Something this natural, when you go with the wind, you don't go against the wind, you go with it.

"I am not Lady Gaga, but I have experienced a lot. And I like to be in touch with people every night all over the world...

"I listen to the people. That was a big reason for my life, maybe the main reason, I'm singing because I love it when people say to me, 'thank you.' I thank them. It's a marriage."

So, 45 years after Iglesias first dazzled his mostly female fans with songs like Begin the Beguine and To All The Girls I've Loved Before, decades of attention he dismisses with a chuckle - "that's just an anecdote, really, although sometimes, yes, it is still the key to the hotel room that gets thrown" - what is his secret to such enduring appeal?

"I have discipline, I look after my voice. I drink only wine," he explains. "Plus passion, professionalism."

"And I still get nervous. I used to get so nervous I couldn't breathe. I don't have to go to the bathroom before every performance like I used to. But when I get nervous now, I say, 'Thankyou for still making me this way.'"

With 80 albums recorded, Iglesias remains an artist in demand. His song La Mer was featured on the soundtrack to Tinker Tailor Soldier Spy, and he most recently turned down the offer to make a compilation of 'world songs' and a love songs concert.

"I just didn't want to go into the studio. I've spent hundreds and hundreds of hours of my life in the studio, and it makes me very tired now. I like to relax."

Dec 2011 - Iglesias receives his awards for being the artist with the most record sales in Latin history, and for the most in Spain, from tennis player Rafael Nadal

Relaxing at the age of means living mostly in Florida with his wife and five children from his second marriage - "they keep me alert" - and studying different cultures, most recently Tunisian cuisine and Orthodox Judaism. For a star with success in one field, Iglesias is remarkably broad in his outlook and curiosity:

"I cannot say I am a complete person, because still the future matters to me very much. My music is only a short time, but my heart has a long life."

One of his favourite things still? Musical duets, when his Spanish gravitas is called for to complete the sounds of other stars, such as Willie Nelson, Diana Ross, something he relishes...

"I love it, because I learn, I have the opportunity to learn from people like Frank Sinatra, Dolly Parton. I sing and I listen.

"It's an amazing learning experience... today I can sing an aria like Placido Domingo."

And what did Julio Iglesias learn from that other stayer, Dolly?

"To go straight in life."

Julio Iglesias' album No.1 - a re-recording of 38 of his most celebrated hits - is available now. Watch him in action with Dolly below...