For the first three years Waterford’s Mount Sion secondary school choir didn’t sing in public, now four years later the group has a viral Youtube hit with 40 million views, and on Friday launched a charity single for World Cancer Day.

Biology teacher Collette Kearney runs the choir, which was started “to help some of the kids stay in school really,” she says.

The Waterford city school has Deis status, meaning it serves students in a disadvantaged area.

“The first two choir teachers walked out, and said ‘you couldn’t teach them’, but I just kind of took them on,” Ms Kearney said.

“For the first three years we sounded appalling, we never sang in public because they had no self esteem or self confidence,” she said.

The choir is made up of students from 26 different nationalities, Ms Kearney said.

On Friday, the choir performed a charity single they recorded with Irish songwriter Don Mescall, Your Love Carries Me, all proceeds of which will go towards cancer charities and research.

The Mount Sion students led six other choirs in a performance ahead of World Cancer Day, in the University College Dublin science centre.

Other choirs included the Irish Sign Language Learners, the UCD staff choir, Solas Cancer Support Centre men’s choir, and school choirs from St Mary’s Newport secondary school in Co Tipperary, Oatlands College in Mount Merrion, Co Dublin, and Loreto College Foxrock in Co Dublin.

Cervical cancer campaigner Vicky Phelan attended the event, along with Stephen Teap, whose late wife Irene was one of the women caught up in the screening controversy.

“I was looking forward to coming here all week,” Ms Phelan said, speaking as students sang Coldplay’s Fix You in the background.

“A lot of what I do is very sombre, very hard sometimes, and I’ve to do a lot of research to get ready for meetings … Today is lovely.” she said.

Before the choral performance Ms Phelan spoke to the students about her personal cancer story, as did others who had lost family members.

“There was one young fellow from Waterford there whose mother died and she was 33, and he stood up and he [wanted to] raise money because he wants to get research done, to try and see if he could find a cure,” Ms Phelan said.

The Mount Sion choir recorded a video for their single in Youghal, Co Cork a number of weeks ago, which features Mr Teap’s six-year-old son Oscar.

Mr Teap got up at 6.30am to come up to Dublin and attend the event on Friday, and said what the choir had done was “absolutely incredible”.