Nine-year-old opera singer Zo Mace is having an extra special Christmas break this year after learning her album has almost sold out, raising nearly £27,000 for the Oxford Children's Hospital Campaign.

News that she has sold almost all of the 5,000 copies came at a particularly poignant time, as her sister Jodie, four, was recovering from a spell in hospital with a viral infection.

It is because of Jodie, who has been treated at the John Radcliffe Hospital, Headington, since she was born with Down's syndrome and holes in her heart, that Zo decided to record the Little Ray of Light compilation.

Many WH Smith shops across Oxfordshire, which are selling the disc, said they had completely sold out of copies by Christmas Eve, while other branches had only a few left.

Mike Ryan, manager of the Oxford branch, said: "There are several left here, but we're still fielding calls from people across the country who want a copy."

Following a spot survey on Christmas Eve, it was estimated that fewer than 500 copies were left in shops, including the Co-op, which has stocked the £5.99 disc.

Zo's mother Linda, 41, of Witney Road, Freeland, near Witney, said: "We have been amazed. It has made Zo's Christmas, especially as she has been so worried about Jodie, who has picked up a bit and is starting to eat.

"She went to the JR on Monday and stayed on the children's ward with suspected pneumonia, which isn't a good thing to have when you have a heart condition.

"She was very poorly, but had fantastic care. It's made me realise just how much we need this children's hospital, because there are currently no facilities for parents and you even have to leave the ward to go to the loo."

Zo's voice has led to comparisons with Charlotte Church, whose best-selling first album Voice of an Angel was produced when she was 13.

The Mail first highlighted the Cokethorpe School pupil's talent and her pledge to help the £15m Oxford Children's Hospital Campaign as a thank-you to the doctors and nurses who have looked after Jodie.

Her sister is due to have more treatment next year, with open heart surgery to rectify a condition called complex AV septal defect.

The CD, which was recorded free by Courtyard Recording Studio in Sutton Courtenay, is dedicated to Jodie and called Little Ray of Light in her honour.

As well as being a success in the shops, Zo has also appeared on ITV's morning show GMTV, won Fox FM's Young Person of the Year award, and earned the backing of celebrity agent Mike Hollings- worth.

But her greatest achievement is raising £26,955 in two months for the children's hospital, which is being built at the JR site and is due to open in January 2007.