THE hallowed auditorium of the Royal Opera House hasn't echoed before with lyrics about "having a rammy" or "doing time in Barlinnie".

But sandwiched between performances by the Royal Ballet and a new production of Les Troyens, 17 people from a homeless drop-in centre in Glasgow will next week perform at the world-renowned theatre as part of the London 2012 Festival.

Organised by music charity Streetwise Opera, the With One Voice event will give a platform to 30 acts drawn from across the UK who have all experienced homelessness.

It marks the first time in Olympic history that homeless people have had an official role in the Games celebrations.

The sole Scottish representatives at this one-off showcase are users of the Lodging House Mission in Calton in Glasgow's east end, who have joined a choir organised by Gorbals-based community music group Givin' It Laldie.

The choir began working with Scottish Opera late last year after Streetwise Opera's founder and chief executive Matthew Peacock met representatives from the Glasgow-based company and encouraged them to engage with homelessness.

The Lodging House Mission (LHM) Choir will perform an eight-minute excerpt from the operetta they devised, Who Killed John King? in Covent Garden on July 2.

The operetta, directed by Lissa Lorenzo and composed by Alan Penman, tells the tale of a policeman who falls in love with a gangster's daughter.

Charlene McKellar, 23, who portrays the bride's sister Laura Queen in the show, became homeless at 16 and slept on the streets while still at school.

She is full of praise for the LHM project that gave her the confidence to secure a full-time job, saying: "It's the best thing I've ever done in my life, honestly. It's completely changed my life"

She added. "You do a lot of things in life and you do it because you don't want to let anybody down, but this time, with Scottish Opera, we've done it because we wanted to do it for ourselves because it's something we enjoy doing."

LHM's education and activity co-ordinator Trina Gibson admits she held her head in her hands when the idea of learning opera was first suggested.

"My first thought was the same as everyone else's: 'Opera?' I thought, 'I'm pushing my luck now'", she said. "But do you know, we led them into it gently. The way they present themselves has improved."

William Leadbetter, 30, who performs the title role, lost his home after he turned to alcohol. He has recently completed a work placement with LHM.

He said: "It has built my self-confidence. I had a battle with drink and stuff, but I've not touched a drink from New Year – I've got my old self back. Working with Scottish Opera has been amazing – I'm just looking forward to London."

Ann McKenna, 57, has been coming to LHM for seven years. She was homeless for 18 months before securing a tenancy in Royston, but continues to use services in the drop-in centre.

Ann, who plays the groom's mother, Mary King, in the show, said: "I had been suicidal at times and being in here has helped me through."

Founded in 1909, LHM is a Christian-based organisation that serves 45,000 hot meals a year. A three-year Big Lottery grant for 20 educational classes within LHM, including choral tuition, runs out in September.

The choir, founded in October 2010 by Shelly Coyne of Givin' It Laldie, premiered its production of Who Killed John King? to a standing ovation at the Gorbals Parish Church in April.

The Glasgow choir will also be among 300 voices at the Royal Opera House performing Gavin Bryars's newly commissioned finale, The Open Road.

"The impact has been huge," said choir leader Shelly. "The biggest thing that we're all surprised about is people's commitment."

Matthew Peacock said he was "astounded by the quality of the performance and the quality of the singing" at the premiere of the operetta in April.

lWith One Voice will be streamed online at www.with1voice.org.uk