'To be honest, making a record was sort of accidental," says Dido, laughing. "I've never been good at forward planning. I'm a very unintentional person."
Twenty years after it was released, Dido's No Angel remains the most successful debut ever by a British woman, unmatched even by Adele.
Her 2003 follow-up, Life for Rent, was another global smash. Across her career, Dido's chilled-out, emotional electronica has attracted more than 40 million album sales. Yet, at the height of her success, she stopped touring and eventually quit live performance altogether.
"I really didn't plan on stopping," she insists. "The last big show I did was Live 8 [in 2005] and at that point I'd been going hard at it for over six years and thought I'd take a little bit of time off. So I was just on a break." She laughs again. "For 15 years."
She quietly released two more albums, without much promotion. The title of her last, 2013's Girl Who Got Away, appeared to confirm she was bowing out of the limelight.
Time off has evidently been good for her. At 47, Dido is the picture of health. She married novelist Rohan Gavin in 2010 and they live together in north London, not far from where she grew up. Their son, Stanley, was born in 2011.
"I have been having a lovely time, being with my family, seeing friends, seeing the world," Dido says. "But the music never stopped. I am always singing, always writing songs. Music is how I make sense of the world. I just stopped playing it to anyone but my family."
Dido has a new album, Still on My Mind, coming in March. Her voice is unchanged, clear and soft with a slight catch as she rises to high notes. Her songs, as ever, are sweet, melodic vignettes. "I'm completely made up of small emotions," she says. "My songs are all little micro-moments, when something small has a big impact on me."
There are homilies to the quiet resilience of ordinary, enduring love (Hurricanes) and a bittersweet ballad about the unconditional love parents bear for children who will one day grow up and leave (Have to Stay). She recognises a thematic thread, "a mixture of nostalgia and regret at choices you have made, and questioning whether they were the right ones".
Dido pauses to consider where these songs have sprung from.
"I'm hurtling into my late 40s. I think when you come out of that initial haze of having super-small kids, you get these really intense waves of feeling that you're not used to having any more. Maybe songs are always a way of looking back. And the older you get the more you have to look back on and the more wisdom you get to look back with."
The album has been co-written and produced with her older brother, Rollo Armstrong, the founder of club band Faithless and a collaborator since her breakthrough.
The siblings were raised in a bohemian, bookish household in Islington. Their late father was managing director of publishers Sidgwick and Jackson and their mother, Clare, was a poet. Dido's given name is actually Florian Cloud de Bounevialle O'Malley Armstrong.
"Such a silly name," she cheerfully acknowledges. Dido was her nickname from childhood, after the Queen of Carthage. "It was," she says, "an unusual household."
From a very early age, she took lessons at Guildhall School of Music, learning piano and violin. By 6, she was playing recorder in a classical ensemble.
"I don't know a life when I haven't actually been performing in some way. And yet it has never come naturally. There's a nervous intensity to it. It is always quite a little trauma."
At secondary school, she sang in a jazz band and answered ads for vocalists in Melody Maker. "People were making electronic music in their bedrooms. I'd go and sing on anything."
She worked at a literary agency and studied law at night, treating music as a hobby that she quietly obsessed about. Meanwhile, Rollo (older by five years) had formed Faithless, for whom Dido sang backing vocals. She recorded some of her own songs in studio downtime at the end of Faithless sessions.
"It was just a fun little project, so my brother and I could hang out after work. To have a cassette of my own songs that I could play myself was as exciting as it could possibly get. There wasn't a thought past that."
Even Rollo discouraged her from pursuing a career in music, thinking she wasn't cut out for the pressures of the business. "I don't think I ever wanted to be famous. I just wanted to prove my brother wrong."
In 1998, Dido signed to the American label Arista. No Angel was released in 1999, with her song Thank You picking up attention on the soundtrack for hit British film Sliding Doors. In 2000, the rapper Eminem contacted Dido asking her permission to sample it.
"And then all hell broke loose," she says. "In a good way." Eminem's breakout hit Stan reached number one in 12 countries, and Dido's album powered up the charts in its wake, selling more than 22 million copies.
When she sings, it always sends her back to "where I was when I wrote the words. I can't help it. For Thank You, I'm always in the bath in my old London flat. I still have the soggy piece of paper in my hand." The song was written about Bob Page, her fiance at the time, who was also the subject of 2003 heartbreak ballad White Flag.
Dido was never a critic's favourite. Somehow her smiling face and ease of tone made her a byword for boring. Her songs are filled with domestic detail, "cups of tea and rain" as she jokingly puts it. "You know what, if that's boring, maybe I am boring!"
She convincingly insists that criticism has never bothered her. "Listen to the music if you want, turn it off if you don't. The rest is irrelevant." Nevertheless, she says she felt a sense of relief in 2008 when her album Safe Trip Home failed to repeat the success of its predecessors (it sold a million copies — almost a flop by her standards). "I love that record. But I realised it was OK to just make music, and let people find it for themselves."
She has focused on family life, insulated by the wealth fame brought her. "I don't need to do this for the money ever again," she acknowledges. "But that was never the motivation. Music is my life."
With that in mind, she is about to go back out on tour in May. "For a long time, my life was music, music, music, and everything else fell by the wayside. Relationships in tatters," she says. "Then, drop everything, wonderful marriage, start a family. It was like they were two separate things. I want to see if I can make them one whole."
Dido's Still on My Mind will be released in March
- Telegraph Media Group