Five days ago, I heard the NCO launch into Mendelssohn's Italian Symphony, joyously, vigorously and with a powerful pooled tone bouncing off the studio's pine walls. Within a minute or so, music director Iona Brown called a halt. "Please, please..." she said quietly, "this is a fairly loud room... but I must hear more piano." So off they set again, quieter this time. But when they reached the passage where Mendelssohn weaves his way back to the opening idea, she shook her head and signalled them to stop. First she asked the violins to play alone, then the cellos, always insisting on textural lightness and dynamic flexibility. She traced the shape of a phrase with her arms, noted the way a particular passage should be bowed, scowled, listened again and smiled. The players were with her all the way, but then they always have been.
During a concert tour in 1994, Brown arrived at Salisbury Cathedral for a rehearsal, having only just lost her mother. The orchestra already knew and responded with the utmost sincerity - initially with silence, then by having a boy soprano intone a heartfelt solo song. The evening concert was profoundly memorable and you can hear it for yourself on a remarkable CD issued by the Salisbury-based hi-fi company Naim Audio.
Iona Brown cites her parents as major influences. Her father Antony was a pianist and organist, and her mother Fiona was a violinist with the Bournemouth Symphony Orchestra. "At 16 she walked up the steps of Broadcasting House," Iona relates proudly, "and said, `I'd like an audition, please, with the BBC Symphony Orchestra, because I've heard they take women.'"
Like daughter like mother, Iona occupies territory where women fear to tread - in her case, the role of conductor - although she didn't have to ask for admission. "It was Rostropovich who suggested me to the Norwegian Chamber Orchestra," she tells me; "he was working with them and they wanted a music director. He introduced me in a very nice, flattering way; they seemed very promising, and somehow it all evolved from there."
The transfer from violin bow to baton brought with it a temporary roster of doubts. "I can tell you that there have been many occasions with various orchestras when I thought: I wish I was a man - because, if I was, those particular rehearsals would have been very different. The man will be called `strong and charismatic', whereas the woman is `neurotic and difficult'. But all that is getting better now, largely because I am more confident. Also, as you grow older, you care less what people think. Nowadays, the music tends to take over. It may not obliterate these problems, but it certainly transcends them. You must have the courage of your convictions; you must be polite; and, as a woman, you must never talk too much. My main concern in rehearsal is - apart from getting the music right - that nobody is bored."
Brown's previous work included a spell in the first violins of the Philharmonia (both Klemperer and Stravinsky, at one time or other, steadied themselves on her shoulder) and, most famously, with the Academy of St Martin-in- the-Fields, where she directed both concerts and recordings. The NCO, however, is built on very different principles, having started out in the mid-1970s as a "summer course" orchestra. "The participants in those courses enjoyed things so much," says artistic administrator August Albertsen, "that they wanted to stick together." The NCO's concert-master Terje Tonnesen was in on things from the first and is currently masterminding a repertoire drive to cover Norwegian, Swedish, Danish, Finnish and Icelandic music, with the intention of making at least two special commissions a year. The 1997 tour employs both advanced students on their final year of study and crack instrumentalists drawn from leading Scandinavian orchestras. "As to the younger players," adds manager Bernt Lauritz Larsen, "first we try them out and then, if they like us - and we like them - they stay."
Brown views herself as a kind of teacher, at least when she's in rehearsal. "We are all individuals," she insists, "and yet today there is, in my humble opinion, always the danger that musicians might end up sounding too alike. I ask players not to copy records, not to copy each other, but to honour their own uniqueness." She admires musical scholarship, but claims that "at the end of the day, inspiration of the moment is everything". She recalls, with particular affection, a recent rehearsal of Mendelssohn's Scottish Symphony. "That wonderful melody in the slow movement cries out for a smooth, silky tonal blend. So I move people around. I might transfer violinists from the back to the front desks, have them adapt to new partners. When they return to their own seats, they play the tune in a completely different way."
New challenges are set for September, when Brown assumes the music directorship of Denmark's Sonderjyllands Symphony Orchestra. "They originally asked me to do a workshop with their string section," she tells me, "but I didn't want to tackle the strings alone - I wanted to work with the whole orchestra. The first rehearsal went very well; I loved them. During the break, the principal second violin told me that the orchestra was looking for a chief conductor. `Oh, really?' I said. `Yes,' he replied... `someone like you.' So, a little later, they took a vote on the decision and were unanimous - it was amazing. I've never been offered a job so fast in my life!"
So, had she harboured conducting aspirations during her playing days. "Never even thought of it," she says decisively. "I was just immersed in the music. I remember my first experience with the National Youth Orchestra - as one of 42 violins playing Dvorak's Carnival overture. I burst into floods of tears; I was totally overwhelmed. I can't explain to you what it was like and I will never forget that moment."
Her first Sonderjyllands concert will include Nielsen's Helios overture, Britten's Purcell Variations and Beethoven's Eroica symphony, or "one Danish, one English and a classic," as she puts it. Further concerts will include such repertory epics as Tchaikovsky's Fourth and Shostakovich's Fifth. Brown is plainly ambitious, but she is also patient. "Simon Rattle once said to me that it takes 10 years to get to know each other and achieve a real sound."
The Brown-NCO alliance proves the point: there is respect and responsiveness aplenty, but no hint of tyranny. "I remember talking to an actor about filming," she says. "If you're not feeling the right sort of thing, he told me, then it doesn't matter how good you are, it will not get into the camera. It's similar with an orchestra. If you feel respect for the players - if your motives for being `authoritative' or firm are right - then I think you are on safe ground. There are many kinds of partnerships and relationships, and there is always the person who is stronger - the one who has `got the job'. I've witnessed some very cruel conductors but I don't think that fear is a terribly good idea: there's plenty of it anyway. After all, I'm not making any sound doing this" - she raises her conducting arm - "but I have got responsibility... I can remember my mother telling me about a lady in the Bournemouth Symphony. She had made a terrible mistake during a performance, but the conductor, Rudolf Schwarz, simply looked elsewhere. After the concert, the woman went backstage to make her apologies. `It was me, it was me,' she said; `I think you thought it was...' `Oh, I did realise,' interjected Schwarz, `but it was my mistake. You see, I make plenty of mistakes - it's just that no one hears them.' Now that's what I call human, humble, decent and honest"
Iona Brown and the Norwegian Chamber Orchestra at the Proms: 7pm tomorrow, Royal Albert Hall, London SW7 (0171-589 8212) and live on BBC Radio 3