Wembley weekend, back in the days of the biannual England vs Scotland fixture, was responsible for many things, including hang-overs and broken goal posts. It was also the spur for a singing career that took Mari Wilson to Top of the Pops, saw her play her hero, Dusty Springfield, in the stage musical Dusty, and later reinvent herself as a jazz artist.

"I used to be shy," she says between mouthfuls of fresh pineapple. "Unlike my brother, who would get up and sing Al Jolson songs at the club my mum and dad used to go to when he was three and get pennies thrown to him, I loved to sing, but not in front of an audience."

That all changed in 1967, the year Scotland beat the then world champions. Mari was 10. The family home in Neasden, being handy for the match, was invaded by her parents' relatives from Clackmannan and Denny and, as always, a party broke out. One uncle played the accordion, another produced his fiddle and everybody had to sing. After much persuasion, Mari belted out the UK's recent Eurovision Song Contest winner, Puppet on a String.

"I was so-o-o nervous. The place was heaving. I mean, they were sleeping on the landing that weekend. But I really enjoyed it," she says. "I remember that as being the turning point."

Her home life played out to an almost constant musical soundtrack, and when Mari got a job as a nanny over on Long Island, she added Philly soul and Barry White singles to the Tamla Motown records she'd collected back home.

Back in London two years later she worked as a secretary, dreaming of being on Top of the Pops. "I think when you want to be something like an artist or a musician, you start hanging around with people who're already doing it," she says. "My brother was in a band, so I'd hang around with them, and then I got to know this guy who had a studio in Wapping and I'd go in and do backing vocals. One night he called and said, There are some guys here who've written this Motown kind of thing and they've tried a few girls but they're not happy with any of them. It's right up your street, d'you want to come in and try it?' It turned out to be Tot Taylor, who wrote my hits, and everything just seemed to click."

Mari insisted on forming a 12-piece band, which at various points included Julia Fordham and a pre-EastEnders Michelle Collins. Word of mouth about the spectacularly beehived Mari Wilson and the Wilsations' stage show ensured that they got plenty of bookings, but they were small scale to begin with and the band was a democracy: Mari was on the same money as everyone else. It was nuts, she concedes now, but when you're drawing the biggest queue to Dingwalls since Blondie and your fifth single, Just What I've Always Wanted, gives you the massive hit you've been dreaming of, the 250-gigs-a-year workload required to keep the band afloat seems like a mere bagatelle.

"I actually loved the band thing, the travelling family moving around in a bubble, going to the States, having people turn up in Detroit expecting Mary Wilson of the Supremes but getting the joke, all that stuff," says Wilson. "And I thought we were making good records. They were raw but they had energy and they were honest. Then, when it came time to make the second album, it all started to go wrong. The record company didn't like the early tracks. My A&R man gave me Dusty in Memphis, which I loved, and told me that was the sort of thing I should be doing, but it would have meant dropping half the band. I wanted to sack the record company but my manager said, No, they drop you, not the other way round. So I sacked my manager. I sacked everybody. I even sacked my hair-do."

What she describes as her "sweeping moment" found Wilson making a complete change of direction. Everything was pointing her towards singing jazz. She recorded Peggy Lee's Dance with a Stranger for the movie of the same name about Ruth Ellis. A saxophonist friend, Stewart Curtis, suggested she formed a jazz quartet.

"I'd turn up in Covent Garden wine bars and sing God Bless the Child, and people would be saying, Isn't that Mari Wilson? What's she doing this for?" she says. "I look back and think, wow that was brave', but it didn't feel brave at the time. I was just happy to be enjoying getting into the car and just driving to the gig. I didn't have to go to photo shoots or think about making records because jazz can just be a live performance thing, if that's what you want it to be."

She didn't record anything between her 1991 album The Rhythm Romance album, and Dolled Up in 2005, recorded as a reaction to splitting from her long-term partner. As well as appearing in jazz clubs, she worked in theatre and was able to forget what it felt like to be famous.

"I got into music because I was a fan - and I still am a fan. Most of my friends, apart from the ones I work with, have ordinary jobs and I like going to the supermarket and just being a mum."

She's not exactly out of the music business loop, though. At Dave Stewart of the Eurhythmics' suggestion she's worked Dolled Up into a one-woman show, The Love Thing, and she was recently asked to take part in a TV series with other stars and bands from the 1980s and 1990s. It was an invitation she politely declined.

"I look better now than I did back then, so I don't need that kind of attention," she says, laughing. "But apart from that, I just want to get on with my music. I have a fantastic band and we do songs from right across my range. I hadn't sung Just What I Always Wanted for about 24 years until quite recently. I still do Cry Me a River, although I tend to do more up-tempo songs these days. Because I'm happier now than I've ever been before."

Mari Wilson plays the Old Fruitmarket, Glasgow, tomorrow.