NOSTALGIC legend has it that ballrooms all across Glasgow used to resound with the following chat-up patter: "Ur ye dancin'?" "Ur ye askin'?" "Ah'm askin..." "Ah'm dancin'!" Natasha Gilmore, who is the founder-director and choreographer of the professional Barrowland Ballet company, has been out and about doing a lot of asking recently.

The result? Some 150 folk are now dancing in her forthcoming community project, and not one of them is under 50. Ages range, in fact, from the mid-fifties to the mid-eighties with a goodly number of the participants totally new to the kind of contemporary dance moves that Gilmore has choreographed for the event she's called Dancing Voices.

The Scottish tranche of this epic venture will be given a public airing during the Merchant City Festival towards the end of July. But the London end of things – yes, the seemingly-tireless Gilmore is running a parallel operation down south – will premiere at that city's South Bank Centre on Wednesday as part of Big Dance 2012 and the Capital Age Festival. "One of our own groups, Golden (from Edinburgh's Dance Base) is joining in the London show," says Gilmore, who has deftly timed our conversation for when her two young children are likely to be napping. "Then the London company Generation X,Y,Z will take part in the Scottish performance alongside groups from Glasgow, Edinburgh, Aberdeen... from all over, really.

"And that coming together, that whole experience of meeting other older dancers and sharing in a process that challenges all the usual stereotypes of ageing that our society is still clinging on to – that, in itself, is totally rewarding for everyone who's involved. It feels like we're giving a voice to people who have tended to become invisible, who are written off – and yet, as I'm finding all the time, they have this incredible energy, this real appetite for life. I'll arrive at rehearsals and find they're all already there, in their kit, keen to get on with learning the next dance. And it is inspirational. Because these are people who have lived through all kinds of social change – not all of it pleasant or easy – and they're willing to challenge themselves by dancing in my choreography."

That choreography, by the way, is not a reprise of the ballroom numbers that many participants might remember from youthful mating rituals on the dance-floors of the Plaza, the Palais and Barrowland itself. Gilmore named her company Barrowland Ballet as a fond salute to the value of social dancing, but she has a serious commitment to contemporary dance-making, whether it's in a professional or a community context. And actually, as last year's highly successful company piece, Conversations with Carmel, showed, she also has a knack for bringing both strands together. One of the outstanding moments in a work that had the cross-generational feel of a family gathering was a sassy video of older dancers, all tricked out in mischievous white and wicked bling, delivering a fabulous routine to Beyonce's Crazy in Love. That, along with the video "witness statements" on how it felt to be pigeonholed and then discounted as apparently past it, pointed to the vitality that Gilmore is channelling into Dancing Voices.

A 40-strong choir, drawn from singing groups across Glasgow, will deliver new vocal arrangements of songs from the past seven decades in a tasty mix that ranges from Nat King Cole to Florence & the Machine. Those decades will be reflected in the mood of each dance section, and that mood will embrace the playful light and poignant shadow of lives that have embraced a world war, the arrival of the NHS, bleak times of unemployment and financial hardship through to the technologies that can now connect the world across the ether – and yet, somehow, can also leave the elderly feeling excluded.

"We were approached by groups – bingo clubs, different cultural groups – who don't normally dance, let alone perform," says Gilmore. "And now some of them are part of Dancing Voices. We've had funding from the First in a Lifetime initiative, and that's really appropriate. We have older people on-stage who are dancing choreography – dynamic moves that are all new to them – for the first time. We're on in the Fruitmarket on July 29, and it's free. So anyone can come along, not just families and friends."

Dancing Voices is on Sunday July 29 at 3pm at Glasgow's Fruitmarket.