For an opera singer, timing is vital. Adriano Graziani’s could not have been better.

Graziani, 32, had called up for tickets to a gala concert last month by Welsh National Opera only to find himself taking centre stage hours later as the original tenor had fallen ill with a cold.

The singing student, a former banker in the City of London, had less than two hours to remind himself of the scores and make his way to the Millennium Centre in Cardiff for a last-minute rehearsal before the evening show.

Now his performance, which received a standing ovation from the 2,000-strong audience, has led to a request for him to perform a lead role with the Welsh National Opera in a production of La Bohème next year.

It is the not the first time that Graziani – who is adamant that he is “not doing anything to these tenors, honestly” – has had a lucky break after the original star has fallen ill. Last year, shortly after leaving the Royal College of Music, he was hired as understudy for the role of Macduff in the Glyndebourne Touring Opera production of Macbeth when his principal fell ill. His performance as a stand-in won him a most-promising newcomer award.

His second lucky break came when he tried to book a seat for a performance in aid of the Friends of Welsh National Opera. “I thought it would be nice to be in the audience for a change so I called up to buy a ticket,” he said. “The man who answered the phone knew me vaguely and asked, ‘You’re a tenor, aren’t you? I don’t suppose you are free tonight? Our tenor is ill.’ ” That evening he found himself performing E lucevan le stelle from Tosca, Core n’grato, a Neapolitan song, the Brindisi Duet from La traviata and Arafa Don, a Welsh song. It was better than an audition.

Graziani, who is studying at the prestigious Cardiff International Academy of Voice, said: “Being half-Italian and half-Welsh I had dreamt of one day singing Italian opera with the WNO – it’s in my blood – but even getting an audition is hard enough.”

After the performance he was offered a three-month contract as understudy in the role of Rodolfo in La Bohème. As part of his contract he will take the lead in a matinee performance in Birmingham next May.

Graziani has come a long way since he was working in a Japanese bank and singing to himself in the office. “I was so miserable every time I walked through the door I’d be overcome by a feeling of nausea. One day my boss called me into his office and asked me, ‘What do you want Adriano? Do you want to work here or do you want to be an opera singer?’

“Of course I said I wanted the job but one day, a little while later, I found myself walking past the Royal College of Music and on a whim I went in and asked to sing for the head vocal coach. He obviously liked what he heard as I got a place.”

After leaving the Royal College of Music he won one of twelve places on a year-long course with the Cardiff academy. The renowned tenor Dennis O’Neill, who set up the academy, said: “Adriano is destined for big things. His singing is exciting and dynamic, and his voice is of the very first rank.”

A spokesman for the WNO said: “This is a great example of us nurturing new opera talent. We have high hopes for Adriano.”

Graziani is hoping to join the list of singers plucked from obscurity who have gone on to become stars. Perhaps the best known is Paul Potts, who was manager of a branch of Carphone Warehouse when he won the television show Britain’s Got Talent last year.

Since his victory he has gone on to have a successful international concert and recording career – and had his crooked teeth straightened.

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