There are many things about which the UK claims to be the envy of the world, but when it comes to choirs, the boast is justified. “It’s one of the things the UK truly excels at,” says the choral conductor Suzi Digby. “More than any other country, we have an amazing amateur tradition. We are the only country with a 1,000-year unbroken tradition of cathedral choir schools. It is one of the things we really do well.”

After years of decline, choirs are becoming cool, spurred by the success of the choirmaster Gareth Malone’s award-winning BBC2 series on choirs. There are now more than 25,000 registered in Britain. They make people feel good. “Choirs are the only place where people come together and express a common emotion,” says Digby, who is also passionate about music education. “That’s why football crowds sing and why choirs are incredibly valuable to society in general.”

In a series that will arguably do more to get people singing than the search for Maria, Nancy or Joseph, the BBC is celebrating the power of choirs in a new series, Last Choir Standing. Presented by Myleene Klass and Nick Knowles, and judged by Digby, the singer Russell Watson and the actress Sharon D Clark, it begins with 60 choirs from across the country, whittles them down to 15 for the studio heats, then invites the public to vote on the last six. The last choir standing will be hailed as the nation’s favourite choir.

Choirs have not always been sexy. “There was this idea that if you were going off to choir practice, you were a sad loser,” Digby says. “People also get a psychological block about singing. Parents say their children can’t, siblings laugh – it doesn’t take much for it all to shut down.” Yet the lung-filling, oxygen-pumping experience is so good at producing a serotonin-fuelled buzz that the Labour peer, No 10 adviser and “happiness tsar”, Richard Layard, recommends joining one for the feelgood factor alone.

The competition’s choirs could not be more varied: a group of hip-hop street kids, struggling to hang on to a musical director long enough to keep the choir together; disabled singers from Northern Ireland; and a kilted a cappella student band from St Andrews, which gets up to 50 coming along to auditions. Some of the choirs are predominantly female. “It’s hard to hang on to men. They prefer to be soloists,” says Perry Alleyne-Hughes, a 55-year-old maths teacher and the musical director of an a cappella group, Sense of Sound. Equally, the Hereford Police Male Choir will not accept ladies. “We’d never live it down in Wales,” says its secretary, Brian Williams. Composed of police and “people known to the police,” which, in this context, means solid citizens such as undertakers, lawyers and doctors, this choir vets members lest villains or arrestees try to exploit their choir connections.

Some are brand-new. Simon Bello, 22, was so passionate about getting a cappella better known that he took time out from his Oxford finals to form a choir for the competition.

“The first time we sang together was the audition. We didn’t have a name. The BBC said, ‘You’ve got to be called something.’ Someone said, ‘Last Minute.’”

By contrast, the Filey Fishermen’s Choir started in 1823 as a preaching band. “The members used to fish from Scarborough from Monday to Friday, go home on Saturday, sing in the West Riding on Sunday, walk seven miles back to Scarborough on Monday at 4 or 5am, then get straight back on their boats,” says the choir’s chairman and organist, Fran-cis Appleby. These days, the choir has dropped the preaching. It sings hymns, especially those associated with fishing. “We sing what we believe, and we hope that everyone gets the message from the words,” Appleby says.

All mention the camaraderie. “It’s been 51 years of my life, and we’re a band of brothers,” says Williams, a retired inspector. His choir has made more than £1m for charity. Members help each other out. “We lost our 26-year-old daughter, Paula, in 1995, and a friend encouraged me to join the police choir,” says Fred Jeanes. “Singing gave me something to concentrate on when grief could have taken over.”

Many of those involved have come via the traditional route of church, county or school choral singing. But not all. “I wasn’t allowed to listen to music until I was 18, in case it distracted me from my studies,” says Silvio Grasso, a 37-year-old graphic designer from Italy. “When I went to parties, someone always had a guitar, and it was embarrassing for me because I didn’t know the lyrics.” In January 2005, a friend asked him to go with him to the newly formed City of Brighton Gay Men’s Choir, and he never left. Three years on, Grasso is chairman of the choir, baking cakes for celebrations and phoning members who have missed a few rehearsals to check they are okay. “I didn’t know I could sing when I joined. I’m still not 100% confident. In fact, in the first concert I was in, I mimed. I’ve never told anyone that before. I didn’t want to make a bad sound for the choir.” With experience came confidence and the adrenaline of performance. “Once you’ve done it, you’re hooked. You want to do it over and over.”

Digby says the judges will be looking for several things. “The technical things have to be in place: blend, balance, diction, interpretation, tuning - if it’s not in tune, I can’t keep with it. But it’s got to communicate, you’ve got to be moved or inspired.”

Which is exactly why choirs sing in the first place. “The choir has allowed me to find part of me I didn’t know I had,” Grasso says. “Even if, when you start rehearsal, you are in a bad mood, when you finish, you are lightened. Everyone should do it. Besides, who doesn’t like music?”

Last Choir Standing will be on BBC1 on Saturday nights from early July

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