Mr Popular keeps on striking the right notes

The tenor Andrea Bocelli will always be the voice of the people, says Jessica Duchen

In his airy studio in London's Clerkenwell, David Bailey is hard at work photographing the most popular tenor on the planet.

Andrea Bocelli poses quietly, reflectors and flashes creating a light-filled aura around him. His fiancée, Veronica Berti – 25 years his junior and pregnant with their first child (Bocelli's third) – hovers with the observing entourage, helping to talk him through the session. The aim of all this is to produce a portrait of the singer for The Official Andrea Bocelli Opus – a project of huge scope and cost devoted to the singer's life and work, running to more than 800 pages. The book is designed as a luxury collector's item and will retail for a four-figure sum. With over 70 million records sold to date, he is beyond the cosmos when it comes to popularity. His Sacred Arias entered the Guinness Book of Records as the highest-selling solo classical album of all time. Yet in the classical field, many are still trying to work out the secret of his success.

Bocelli's fans don't bother with operatic snobbery: ever since his first album went platinum in 1994, they have bought his discs and flocked to his performances. Recently he sang in Central Park, New York; a DVD of the occasion will be released in November. During his visit to London, when I caught up with him, he also appeared in a special 50th anniversary edition of Songs of Praise on BBC1.

But critics are not kind to him. He gave a recital at the Metropolitan Opera in New York in February – a programme of songs by composers ranging from Handel to Fauré via Beethoven and Strauss, taken from his latest album, Notte Illuminata – but the New York Times slated his "bland homogeneity" and "dogged, unrelenting quality".

Fans rave over the melting quality of his tone, its gentleness, its directness. Detractors grumble about its lack of expressive range and its pinched, nasal patina.

Bocelli, who is now 53, seems unperturbed by the apparent divide between critical dismissal and popular embrace. "I think in the world of opera that's the way things are," he comments, via an interpreter (though his English is not bad). "There's criticism for absolutely everybody. And in a way this makes it more interesting because, after all, discussion is life."

Connecting with others through singing, he adds, is "just a question of being oneself". He doesn't talk about his blindness. Having been partially sighted from the start due to congenital glaucoma, he was rendered completely blind by a football injury when he was 12 years old. "When I was a child, everywhere people asked me to sing – in school, in church, in my family, everywhere," he says. "I understood that it was my destiny."

One question dogs Bocelli's steps in the classical world: can he really be called an opera singer? Or should he be taken on board simply as "easy listening"? Unlike certain other "crossover" singers, though, Bocelli has indeed performed and recorded entire operas – he will appear in Gounod's Roméo et Juliette in Genoa next February ("I'm studying!" he laughs) and a recording of it will follow. What, then, is Bocelli's secret? The appeal of his struggle against adversity? The sweetness of his voice? Clever marketing? All of these play a role. But here's a thought: the quasi-superhuman gifts of a Domingo are glorious, yet it's hard to identify ourselves with them. Bocelli's is the voice of the rest of us: we dream, we battle on, we do the best we can with what we've got. His voice could have been great. His triumph is that it doesn't matter that it is not. His success is our absolution.

To preorder a copy of the Bocelli Opus go to www.krakenopus.com/family/bocelli