Blonde, soft-spoken, slim and 29, Alison Balsom is as far removed from the traditional beer-bellied image of a brass player as it's possible to get. Yet a brass player she is, and a fabulous one, too. Her new EMI recording of classic trumpet concertos is mesmerising. In her hands that tangle of tubing seems as subtle and dextrous as a violin. It's not that she invests this most macho of instruments with "feminine" qualities, as some critics have suggested. It's more that she makes the trumpet sing with an irresistible exuberance and eloquence.

She's not naive enough to believe that her looks haven't helped her up the ladder. "I know that many opportunities to come my way depend quite a lot on my image," she says. "I might not have a record deal, for instance, if people felt that they couldn't sell my CDs to a public that isn't primarily interested in classical music."

Does that irritate her? After all, a male trumpet player would just be judged on his technique and musicality. "It's a fine balance," she replies. "You want to pull in the people who like looking at nice pictures of me on magazine covers, but not put off the connoisseurs who are interested in the music. My last disc was called Caprice, and had lots of flashy short pieces on it. I felt it came dangerously close to being dismissed as yet another 'crossover' album by a pretty girl who's as much about fashion as music. That's not what I'm interested in at all."

She will have to work hard to avoid those accusations all over again when she embarks on her next project: an album, possibly followed by a world tour, with another pin-up girl of the British classical music scene, the soprano Kate Royal. "Kate has a similar attitude to mine," Balsom suggests. "She takes her performing very seriously, but people just want her to walk around the stage in a bikini."

At least Balsom's current EMI disc is of unimpeachably serious repertoire. Taken together, the four concertos brilliantly demonstrate the development of the trumpet through the 17th, 18th and early 19th centuries. The earliest, by Giuseppe Torelli, was written for "natural" trumpet - when the instrument had no valves and could play only the harmonic series. Then comes a delightful oddity by the Czech composer Jan Krtitel Jiri Neruda. "Actually, that's a bit of a cheat," Balsom admits, "because it was written for the corno da caccia, the hunting horn, which no longer exists. But trumpet players play it all the time."

Finally, the disc includes the two masterpieces - by Joseph Haydn and Johann Hummel - that established the soloistic credentials of the first trumpet capable of playing all the notes of the chromatic scale. "Both composers were inspired by the playing of this one virtuoso, Anton Weidinger, who invented a 'keyed' trumpet in the 1790s," Balsom explains. "The Haydn concerto I've played since childhood - I played its slow movement for my Grade VI exam, when I was about 11 - but it's such a wonderful piece that I never get bored with it. On the recording I've tried to strip it of all the additions and vibrato that later players put into it, and give it a Classical feel without losing its heart."

Balsom was at primary school in Royston, Hertfordshire, when she first put a trumpet to her lips. "I had free tuition at school, and I also started playing with the local brass band in Royston. Actually, I still go back and play carols with them on Christmas Day. It's wonderful. The same players are still there. I think some of them have been playing in the band for 50 or 60 years." She found that tootling the trumpet and cornet came naturally to her. "With brass instruments, you either have the embouchure for it, or you don't."

Her parents were not musical - her dad was a builder, and her mum placed children with foster families - but they realised they had a special talent in the family. "When I was 10, as a special treat, I was taken to hear Håkan Hardenberger play the Hummel concerto at the Barbican."

This first encounter with the dazzling Swedish trumpet player (he later became one of Balsom's teachers) defined her life. "I remember that concert as if it was a week ago. I just thought, 'That's what I want to do - stand up there and play trumpet solos.' And even when I got older, and it became apparent that this wasn't what most trumpet players did - they mostly sit at the back of orchestras, not play concertos - my passion was still to be a soloist."

She played in the National Youth Orchestra and studied at the Guildhall School of Music in London. But it was when she moved to Paris, she feels, that she really learnt her trade. "The French trumpet-playing way is much more soloistic, much less orchestra-focused, than in Britain."

It was in Paris that she switched to the C trumpet, a more virtuosic, woodwind-like instrument than the usual B-flat trumpet. "I also inherited a fine C trumpet from a friend who died," she says. "So there's a sentimental aspect to playing it, as well."

Though she appears as cool as a cucumber on the concert platform, she admits to colossal nerves. "My friend, the violinist Alina Ibragimova, never gets nervous. I just don't understand people like that. I think she must be a different species of human being. When I was young I used to be consumed with nerves. I very rarely slept the night before a big concert. The only way I've been able to be a performer is to realise that nerves are good: it means you are excited and you really care."

She finds that the touring now demanded of her, as a rising soloist on the international scene, is exhausting and sometimes demoralising. "Being in hotels by yourself, waiting around airports - you feel your life is being taken over." Two things, apart from music, keep her grounded and sane. She has sailed since her childhood, and now has a day-skipper qualification. "My dad keeps his boat at Brightlingsea in Essex, and I go there a lot. That, or skiing or surfing, is a brilliant way to switch off."

And the other is her "amazing" boyfriend. After her brief but much discussed romance with the Russian violinist Maxim Vengerov she has - sensibly, many musicians might say - fallen in love with someone who isn't in the business at all. "He's a dealer in antique silver, the same age as me. And he's given me a tremendous sense of perspective. Friends in Winchester, where I live, tried to set us up together a year ago. I wasn't pushed into it then. I was in a different place as a person. But eventually I thought, 'This is right for me.' "