GLOBE-trotting New Zealander Hayley Westenra is said to have the voice of an angel. Since being spotted busking on the streets of her hometown Christchurch, her melodious sound has mesmerised people the world over.

At only 16 years-old she toured America and Asia after her first album, Pure, became the fastest-selling debut album by a classical artist.

Hayley, who has now settled in London, remains acutely aware of her good fortune and is as committed to supporting worthy causes as she is to singing and song writing. The 22-year-old is involved in several charitable endeavours and at 16 became the youngest ever ambassador for UNICEF.

"I was asked to be a goodwill ambassador by the New Zealand team for UNICEF," she said. "At first I thought it would be too big a role to take on at such a young age, but I decided that if they thought I could help, maybe I could. Supporting charities is important to me because I am living such a blessed life, I feel I should give something back."

Last month Hayley launched the Poppy Appeal with Dame Vera Lynn at the Horse Guards Parade and performed at Royal British Legion's Festival of Remembrance at the Royal Albert Hall on Remembrance Sunday.

She said she is making it her business to raise the profile of soldiers fighting for their country in Afghanistan and explained how she became involved in military causes: "A few years ago I was asked to sing in Passchendaele, Belgium, where a First World War battle took place involving a lot of soldiers from Australia and New Zealand. While I was there I was shown a name of one of my relatives on a memorial. My family history was suddenly brought to life," she said.

"Some time later I was invited by the British Legion to sing for the British troops in Basra. Having been out there to meet all the young service people I feel some responsibility to keep them in the public eye."

Hayley said that it was always her dream to be a singer. And after her music teacher recognised her talent she started auditioning for local singing events. By the age of 11 she had racked up 40 stage performances. She also took her talent to the street and started busking.

"I used the money I raised to make a recording and then sold my CD as I busked. A local journalist approached me and invited me on to her show. A record company then got in touch and signed me up aged 13."

Her four albums, Pure, Odyssey, Treasure and her best of collection, Rivers of Dreams, have sold more than 400 million copies worldwide.

But her repertoire is also impressively crammed with television and film work — she has recorded the theme for Al Pacino's Merchant of Venice, and tunes for two Disney films and the theme tune for BBC's drama series Jekyll and ITV's, Flood.

"I started out singing classical songs, and I still do, but I also write my own which are more folk and pop orientated," she said. "People like to put singers in a genre, so if I had to be in one I guess it would be classical."

She is coming to Exeter next month as part of her national winter tour before heading home to New Zealand for Christmas, and setting off again on another international tour.

Devon County Youth Choir is opening the concert, which takes place at Exeter Cathedral on December 3, at 7.30pm. It will be a mix of Christmas songs and some of Hayley's classics. Tickets are £17.50, £19.50, or £23.50, from See Tickets on 0871 2305573.