A doctor whose online campaign helped an NHS choir beat Justin Bieber to Christmas Number One has said she is “over the moon” with the result – and added that the choir are now hoping the pop star will join them for a concert.

Harriet Nerva, a junior doctor at Hinchingbrooke Hospital in Cambridge, launched a Facebook event in late October to land the Lewisham and Greenwich NHS Trust Choir the top spot in the UK’s music charts for their single “Bridge Over You” – a mash-up of Simon and Garfunkel’s “Bridge over troubled water” and Coldplay’s “Fix You”.

The former JFS pupil said she had heard the song – which was originally recorded in 2013 after the choir appeared on Gareth Malone’s TV programme “The Choir: Sing while you work” – after a particularly gruelling day at hospital. She was reminded “how proud I am to work for the NHS”, and so set out to raise as much public support as possible for the public health service.

“Morale in the NHS is really low,” the 26-year-old said, with junior doctors locked in rows with the government over changes to their contracts and cuts being made to student nurse grants.

Dr Nerva, who belongs to Belsize Square Synagogue, immediately took to Facebook and Twitter to drum up interest and support, creating an online event that said: “I love our NHS so much that I’ve started a campaign to get it to number one in the charts this Christmas.

“Get our NHS to top of the pops and to the top of the agenda. Celebrate and save our NHS!”

The campaign took off more than Ms Nerva could have imagined - attracting hundreds of thousands of supporters in just a few days. Two months later, the choir, which is made up of NHS doctors, nurses, physiotherapists and administration staff, are at the top of the charts, and 52 million people have joined Ms Nerva’s online event.

They even beat international pop star Justin Bieber to clinch the top spot, amassing a total combined chart sale of over 127,000 copies to his 97,000. Mr Bieber was so moved by the choir that – before the final tallies were revealed – he publicly endorsed them, tweeting to his 72 million followers: “Let’s do the right thing and let them win.”

When the result was revealed, he wrote on Twitter: “Just heard the news. Amazing. That is what Christmas is all about.”

“We were overwhelmed that Justin Bieber backed us,” Dr Nerva said. “This was a grassroots campaign run by a small team on top of our day jobs and we never expected we would be competing with someone like Justin.”

She added: “Our next move is to organise a concert with the choir and get Justin along to perform with us.”

Proceeds from the single’s sales will go to charities including Carers UK and Mind, as well as the Scottish Association for Mental Health (SAMH) and the Northern Ireland Association for Mental Health (NIAM).