Members of the Lewisham and Greenwich NHS Choir were told about the plan on Wednesday.

Hollywood rights to the choir’s story have been bought by top LA-based film producer Julia Verdin whose credits include The Merchant of Venice starring Al Pacino and 2 Jacks starring Sienna Miller. She will take the idea to the Cannes Film Festival from May 11.

The movie will feature back stories and the personal journey of the choir members and their work. It will tell of the individual and collective pride in the NHS which drove them to record Bridge Over Troubled Waters and create a wave of national pride in the NHS taking the coveted Christmas Number One spot in 2015.

Physiotherapist and choir member Caroline Harboard said they were “over the moon” and “completely overwhelmed”.

She said: “We are just a bunch of NHS health care workers who sing – it’s a bit mad but very exciting.

“We have gone from being a work-based choir to being on the TV and then get a Christmas number one and then a record deal, it’s unbelievable and a bit of a dream.

“We had no idea when we started that it would come to this. It was an amazing opportunity just to be on the TV show and even now it’s still not really sunk in that we got the Christmas number one.

“The film deal is still in negotiation but we are completely overwhelmed. It’s quite surreal.”

And she said that even if it turns into a Hollywood blockbuster they will still maintain their jobs in the NHS.

She said: “It’s great for Lewisham Hospital and really good news generally. We are all very proud of the Trust we all work for and the choir. We’ve achieved more than we ever thought – it’s hard to find the words.

“But at the moment we are all very dedicated to our day jobs within the NHS. The choir is about celebrating the NHS and all the great work that happens within it.

“It would be wonderful to be part of and I hope Justin [Bieber] could get a cameo role as his support was so important – we aer also still hoping he will do a duet with us in the future.”

Julia Verdin said: “I believe people will love watching this remarkable and uplifting story which has already touched the hearts of millions in the UK.”

Professor Jonathan Shalit OBE, founder of London’s largest independent talent agency ROAR Global which now manages the choir and who landed the movie deal, said: “This choir, made up of a typical group of the wonderful people who work in our NHS, have tapped into what is too often the unspoken pride felt by millions in the work of one of the nation’s most cherished institutions.

“The coming together of their story and that of the incredible work of NHS truly is the stuff of movies and I am thrilled that Julia Verdin is on board to create a film which will resonate globally.”

The 30-strong choir was set up in 2012 to take part in Gareth Malone’s TV programme Sing While You Work but were narrowly beaten in the final.

Made up of staff from across all areas of the NHS including nurses, doctors, physiotherapists, midwives, porters and administrators, the choir perform regularly for hospital patients and the local community, as well as singing in concerts across the UK.

Earlier this year they announced they had secured a two-album deal with Decca Records. Decca is part of Universal Music which is also home to Justin Bieber and who urged his 81million Twitter followers to buy the choir’s single at Christmas.

The album will be released on June 3 and the Trust has said a minimum of £40,000 from its sale should be paid to its charitable funds.