the Moat House hotel near the Top of the Pops studio in Elstree is a strange, rootless sort of place, just off the A1 with a car park full of Sierras. Christmas decorations are going up in the lobby as Heather Small - vocal powerhouse of the sleek and sturdy pop vessel known as M People - makes her entrance. In person, Small is nothing like the Amazon she looks in videos (in fact the widespread use of her full name as cockney rhyming slang for tall needs serious reconsideration) but she still seems a force to be reckoned with. Surveying the rather measly display of fruit on offer in her room, her response is instantaneous: "If there's some more grapes, Amanda, that would make me happy."

Small's entourage is three in number - make-up woman, press officer and the craggy, black-clad form of Wigan and England rugby league star Shaun Edwards. "We've both got very busy schedules," Heather explains, "and if you want to spend time together, you've got to take your chances where you can." Shaun and Heather met "through friends: he said hello and I said hello" and have been together for about two years. This is already good going for a partnership at their lofty celebrity altitude. "No one else'll have us," observes the grinning Edwards, to lusty guffaws.

The resting sportsman's decision to sit in on the interview is initially cause for some trepidation (a particular in-pursuit-of-the-ball incident with an unfortunate Australian opponent looms large in the memory) but he proves to be a kindly, tea-pouring presence. "I don't mind listening," he affirms resignedly, "she's not told me half of this herself."

Even in her personal life, it seems, Heather Small is renowned for that rarest of all qualities in a famous person: discretion. At 29, a star more fully-fledged than many whose faces and opinions are hard to get away from, you can count the solo interviews she's given on the fingers of one foot . "I don't think I'm very good interviewing material," she says, rather ominously. "I sing but it's not for celebrity status."

One of the most interesting things about M People is the way they have united the most modern dancefloor craftsmanship with old-fashioned ideas of being in a band. When first founded by the renowned Hacienda Club DJ and one time Dire Straits roadie Mike Pickering (whose initial was the origin of the M), M People were going to be a loose collective on the Soul II Soul model, changing personnel as the occasion demanded. But the songs Heather sang were the ones everyone liked, and so they became a band. The four-strong core of Small, Pickering, ex-Orange Juice man Paul Heard and percussionist Shovell is now renowned for its close-knittedness. They've even been known to go on holiday together.

M People started at the turn of the Nineties: a bad time for singers. The new sampling technology integral to the dance music boom of the late Eighties had separated voices from their owners, allowing them to be cut up and moved around at the whim of producers and DJs. It was the era, as Heather puts it, of "Who sings? Who cares?" In the context of dismembered old soul vocals being mimed to by models it was perhaps understandable that some people weren't sure Heather was singing on early M People releases - "A lot of people thought because of how I sounded that I ought to weigh about 20 stone" - but that didn't make it any less galling.

"The only way round it," Heather explains, "was to play and sing live. I think people know I'm the singer now." On M People's current tour there are 11 performers on stage, and it is in no small part thanks to them that the days when two keyboards and a singer could pass as a live pop performance are pretty much over. This made it doubly ironic that when M People's Elegant Slumming album deservedly won the 1994 Mercury Prize, there were attempts in certain indie-supremacist quarters to demonise them as a "manufactured" dance act (as if the artful constructions of Mercury rivals Pulp and Blur somehow grew organically from the earth).

Heather is phlegmatic about this - "You've only got to worry about the people who think well of you" - but the memory of suggestions that as a black female singer with white musicians behind her she must by necessity be some kind of puppet still prompts her to understandable fury. "It's very offensive - very sexist and very racist - the worst part of it is that these are people who consider themselves to be liberal-minded."

M People's triumphant showing at the 1994 Glastonbury Festival must have made uncomfortable TV viewing for anyone deluded enough to believe that one type of music has more intrinsic spiritual value than another. Heather admits she was "extremely nervous" before her encounter with Britain's great unwashed. "For a week before, I made Shaun's life hell, but then to see all the different types of people that were there singing along with our songs, that made me happy." Standards still had to be maintained, though. "Somebody asked me afterwards 'Heather, did you stay in a tent?' I said 'mmm-mmm, not this girl'." It would be fair to say of Heather Small that she likes her home comforts -"fruit, camomile tea and a decent room" being top priorities. In defence of an unnervingly ascetic regimen - no drink, drugs or tobacco, and a daily 90-minute workout - she cites professional pride and Frank Sinatra - "a real lad" - swimming 40 lengths a day. "I've always put health first," she maintains cheerily, "because I'm asthmatic, and to be asthmatic and a singer is not the best combination." Becoming a vegan has improved matters - "you get mucus forming from dairy products" - but when she was younger her asthma was a real problem.

"I was never hospitalised," she remembers gratefully, "but the doctor thought I should leave this country and go to the Caribbean because it was too cold in the winter." Heather was born here. Her parents emigrated from Barbados to Britain in 1963. Her dad worked for London Transport and her mum for Waitrose in Finchley. It was decided she should stay in the UK. "My parents didn't want me to grow up without them and my sister."

Growing up in Ladbroke Grove, west London, Heather Small "always felt like a singer" but - discreet as ever - didn't really tell anyone: "All my music teachers at school must be very surprised." She practised with a hairbrush microphone in the bathroom and sometimes with like-minded friends. When she was very young she also used to do shows for her mother and sister, forcing them to sit down and listen to songs of her own composition. But even under the closest questioning, she refuses to remember any examples.

She will confess to early unease about the depth of her voice. "At the time I began to think I was really interested in singing, it was the Seventies and lovers rock was happening. Those singers' voices were so high like the girl [Janet Kay] who sang 'Silly Games', that I was like, 'Oh my God, if that's what you have to be like to be a singer I'll never make it'. I used to listen to Mavis Staples and pray."

When she was 18 she replied to an advert in Melody Maker asking for a singer who liked Gladys Knight and Aretha Franklin, and joined a group called Hothouse, which eventually - some six years on - turned out to be her gateway to M People. Hothouse's finest moment was one of their earliest proper gigs, supporting Barry White at the Royal Albert Hall: "I just stood there and sang with my eyes closed, hardly moving." Tonight, M People play their third successive night there, and a bit more movement will probably be required.

At the interview's end, Top Of The Pops calls. Shaun wants to go home. He is exhausted after a hard morning in rehearsal - "I can't stand the pace: I couldn't cope with the hours this lot put in." Heather is off to sing M People's version of the Sixties classic "Itchycoo Park," the work, piquantly enough, of Brit-pop godfathers The Small Faces. Isn't that a very summery sort of song to put out at the end of November? Heather laughs. "If you only want to feel good in the summer, then you really are limiting yourself."

8 M People play the Royal Albert Hall (0171-589 8212) tonight and tour till 16 December, with summer dates just announced at Alton Towers, 15 June and Crystal Palace National Sports Centre 16 June (for details call 0115 934 2000)