Silver Comedy Stand-Up of the Year: 'Heard the one about the old ones being the best?'

A Slice of Britain: No? Well, turn up your hearing aid! Two dozen elderly comics go gag-to-gag for the title

With her tightly curled grey hair, oversized cardie and sweet smile, Julie Kertesz looks like the sort of granny who fishes in her pockets and hands out fluff-covered humbugs. But then she opens her mouth: "I'm 77 years old; what the fack am I doing stand-up for?"

Rather than antique sweets, she dishes out a profanity-filled comedy spiel that arcs from biting reflections on catching cheating lovers to the perils of shaving unwanted female facial hair.

She and 23 others are vying to be the first ever Silver Comedy Stand-Up of the Year, being held in a small hall in Leicester's community arts centre as part of Dave’s Leicester Comedy Festival, the longest running festival of its kind in the UK. The only criterion for entry is that you must be older than 55. While stand-up is booming in Britain, both on stage and on television, the number of performers from the older generation is dwindling.

Silver Comedy has spent years organising comedy lessons in nursing homes and daycare centres for the elderly around the country. George Baddeley, the organisation's managing director, decided to launch the contest to bring older comedians to a wider audience. "Comedy is like the music industry in that it's easier to break in as a young person, but you'll have a few established bands that [hold on to] success as they get older. You don't see new people breaking in who aren't young – this is a chance for them."

Contestants in the first heats each have to deliver a three-minute set. The qualification rounds present performers with a tough crowd: only judges and their fellow contestants, most of whom are too tense about their own looming performance to laugh.

Don Clark's hands shake on his walking stick as he waits for his turn. The 71-year-old from Wakefield has only performed once before and is struggling: "Waiting is the scary bit." He spends most of the next eight acts looking apprehensively at his shoes.

When his turn finally comes he opens well: "I'm Don Clark and if you're the kind of person who likes making cheeky anagrams then that makes me Old Crank." Later, he freezes, forgetting his next line and crunching the microphone against his forehead in silence for what seems like an age.

Bob Renshaw, 80, with white hair and white beard, looks like Central Casting's idea of a doddery pensioner. He has never done stand-up in front of a proper audience but – emboldened by a course last year – is taking the plunge. "I've always done a bit of writing and thought that some of it was quite amusing," he says. "The only older people you generally see doing stand-up are those who've been doing it since they were young." When he gets on stage he is laugh-out-loud funny.

As the day wears on, one of the elderly comics has a nap between sets, his flat cap pulled low over his eyes and his mouth ajar; another spends much of the competition asking her neighbour to repeat the gags she is too deaf to hear.

Charmian Hughes, from Peckham, south London, is the spring chicken of the bunch at 55, but she has some of the best age-inspired gags: "One minute you're playing on your Wii and the next you're sitting in it." She aims this at a pair of particularly fresh-faced students in the front row. Ms Hughes has been on the stand-up circuit, on and off, for several decades, but says being older makes it more difficult. "Your profile just goes down and you're surrounded by young boys."

Shelley Bridgman, a 63-year-old transsexual, who has been on the comedy circuit for several years, gets some of the biggest laughs. "I was born with a bit of a birth defect. I was born male, grew up, spent 30 grand and now I'm gorgeous." The audience guffaws.

The 24 have to endure an agonising wait to be whittled down to 10 for the evening's final and the chance to take home a prize. Don has not made it, and goes home early looking dejected. Bob, Charmian, Julie and Shelley are all through to the next round.

The final 10 battle again, this time in front of a paying public of 100 or so and a panel of five judges. Shelley's skit on being born a man raises the biggest laughs again and she takes home the prized golden microphone for Silver Comedy Stand-Up of the Year. Potty-mouthed Julie Kertesz bags Best Old Newcomer and is sporting a victory grin. "My pleasure is not to win but to make people laugh and to challenge stereotypes about age," she says.

Benjamin Rushton, an 18-year-old student at the University of Leicester, emerges from the show wide-eyed. Like many in the audience, he has had his preconceptions rattled. "It's quite shocking to see how sexually frustrated the older generation seem to be," he says. Ms Kertesz and the others have driven home their message. "I know it was specifically older comedy but I didn't see it as that," says Mr Rushton. "I just saw it as good comedy."