Christine Bovill has a lot to answer for. You wouldn’t know it from looking at her – a vivacious blonde who exudes warmth and good humour – but she routinely turns people who hear her sing into babbling emotional wrecks and, in the process, provides a sort of therapy.

I should know. The first time I heard her perform her Piaf show at the Edinburgh Fringe, seven summers ago, the experience unexpectedly put me through the emotional wringer – so much so that I was still sobbing quietly by the time my train reached Queen Street Station. I gave the show a five-star review.

For Bovill, a 46-year-old Glaswegian who is now one of the Fringe’s biggest stars as well as a regular headliner on stages all over the world, that performance – in the capital’s Central Library – was a turning point. The five-star reviews it earned inspired her to quit her day job and focus on her singing and writing career.

“Up until that night,” she says, “I was still developing a sense of confidence in the show. It had had a narrator – it had been Edith Piaf’s life story, with a wee bit about me thrown in. I kept this script on the stage, not to read but just as an anchor and the night you were in, I put it on the music stand beside me as I always did. After the second song, I looked over at it – and it was the directions for driving to the venue!”

Rather than panicking – or even giving away the fact that she had just lost her “anchor” - Bovill spontaneously re-wrote her show as she went along. “It was one of those moments where you think: ‘to hell with it … people here probably know Piaf’s story so I’m going to interweave mine into it’ - and it’s developed more and more since then. Now, when I’m selling my show – when I write to theatres – I have to tell them that this is my story; the story of a girl from Glasgow. It’s as much about me as a musical tribute to Piaf. I say more about myself now than I used to.”

And indeed, it was the humour in Bovill’s account of how, as a French-flunking teenager, she discovered and became obsessed with Edith Piaf that made this particular Piaf show work so beautifully. Her own story offset the darkness and tragedy of Piaf’s painful biography as well as the raw emotion conveyed in her gut-wrenching performances of the Little Sparrow’s songs.

The show also stood out from other Piaf tributes because Bovill didn’t imitate her iconic hero – there is no hand choreography, no attempt to mimic the way that the frail and vulnerable-looking older Edith would morph into her proud, defiant alter ego when she started in on her famous signature song Non, Je Ne Regrette Rien. Bovill’s voice doesn’t even sound like Piaf’s.

Instead, she paid homage through her obvious affection and admiration for Piaf and through her honest readings of her songs, all sung in such a natural French accent that you forgot you were listening to a Glaswegian.

This wasn’t the first time that Edith Piaf had opened doors for Christine Bovill. Just as the Piaf show proved to be the catalyst for the Scottish singer’s current career, so her discovery of the music of Piaf had been a life-changing event decades earlier. Bovill is fond of a Graham Greene quote which illustrates this perfectly: “There’s a moment in every childhood when a door opens and lets the future in.”

For Bovill – who grew up in Mollinsburn, near Cumbernauld – that moment happened when she was 14. “A priest friend of the family came round one night with a record he thought I should listen to because he knew I had been collecting old jazz records – I was listening to a lot of 1930s stuff at the time.

“The singer was Edith Piaf. I recoiled in terror because he told me she was French – and I loathed all things French at the time (especially my French classes at school). But he said ‘No, side A is sung in English, listen to the second song on Side A, a song called No Regrets’. So I put on No Regrets. And that was it – I was hooked!

“Her voice was like nothing I’d ever come across before – the purity of her phrasing, the power and the unique emotional quality in her voice. I was also immediately taken with the songs themselves – glorious melodies and arrangements. Along with Billie Holiday – whose style was very different – she became an obsession for me.”

Not only did Bovill become hooked on Piaf (so much so that she had a Piaf CD box set booked out from her local library for four years), but she also got hooked on the French language. “I started living, eating and sleeping French so I could understand what she was saying and could sing her songs.”

From being the girl who wouldn’t succeed in French class, she went on to study French at Stirling University. During the obligatory year abroad as an English language assistant in a school, she landed a scholarship to study music appreciation at Poitiers University, and she spent some of her free time jamming with fellow students.

Back in Scotland for the final year of her degree course, she landed a couple of weekly gigs – singing standards and French chansons - at the Inn on the Green, and commuted to Stirling every day for lectures and tutorials.

After graduating, she worked as a French and English teacher – but continued to sing in her spare time. “It was only when I started songwriting, eight years into my teaching career, that the balance shifted more towards singing. And it was only when I released my first album - Derby Street - in 2009 that I quit the classroom for good.” Derby Street, in Kelvinbridge, was where an “emotionally fragile” Bovill set up home alone after her marriage ended, and it was here that she effectively launched the current chapter of her singing career, “pouring” her heart out into that debut album.

These days, Bovill is in a much better place. She lives with her partner not far from her old bachelor flat, and her singing career has sky-rocketed. Just four years after that breakthrough, five-star Piaf show was the talk of the Fringe (for anyone who could talk between sobs and blowing their noses that is), Bovill pulled off a terrific coup by bringing the composer of Non, Je Ne Regrette Rien, Charles Dumont, to Edinburgh for her Piaf centenary show.

Bovill is back at the Fringe next month, and at the Fringe By the Sea in North Berwick. She will be performing Piaf as well as her more recently developed Paris show. What, one wonders, is “la différence”?

“The Paris show has evolved from the Piaf show,” says Bovill. “It’s a glorious celebration of that period, from the 1920s to the 1950s (just before the advent of the “le yeh-heh” – rock n roll), when French songs were all about lyrics and the importance of storytelling with the rhythms of the French language. It includes songs by the likes of Kurt Weill, Charles Trenet, Juliet Greco and Charles Aznavour.

“I’ve chosen songs which were hits in English and which people maybe don’t realise started off life as French – for example Let It Be Me, which was a hit for the Everly Brothers who are big heroes of mine, What Now My Love, Barbara etc.”

Paris and Piaf take up most of Bovill’s August diary, but what lies beyond the Fringe, so to speak? “Well, I’m keen to push the other side of this schizophrenic career – the troubadour, singer-songwriter side. It’s taken two albums. I’m at the stage where I know the sound I want – a sort of pan-European, folky jazz, Leonard Cohen, eastern European sort of thing , with accordion, double bass, violin. I do a lot of work with the Hot Club of Glasgow – gypsy jazz – so I’ve got a lot of songs on the go!”

Which, I think, translates as: watch this space ….

* Christine Bovill’s Paris show is at the Fringe By the Sea in North Berwick on August 5 and at the New Town Theatre, Edinburgh on August 14th & 21st. Her Piaf show is on at the New Town Theatre on August 13th & 20th. Visit www.edfringe.com or www.christinebovill.com for details.