"Right, let's go," shouts the conductor Valery Gergiev, and with screeching violins and a clash of cymbals, the orchestra surge into Prokofiev's tumultuous Third Symphony. They expertly negotiate the music's controlled hysteria, adjusting instantly to the maestro's cryptic commands: it's hard to believe this is a piece they haven't played for years. Complimented afterwards on sorting it so fast, the co-leader politely demurs: "Whatever Gergiev demands in rehearsal, we know he'll demand something totally different on the night."
Rehearsing Verdi's Falstaff with Sir Colin Davis a few days later, Britain's finest orchestra might be on another planet. This work starts with a high dive into a thicket of musical argument: it's new to most of the players, but again, you wouldn't know. Their resident maestro steers them invisibly towards his goal: like thoroughbred racehorses, an occasional nudge is all they need.
The London Symphony Orchestra really is some band, as the names celebrating its centenary next Wednesday attest: Rostropovich, Midori, Sarah Chang, Alfred Brendel, John Williams and Dave Brubeck are just some of the stars who will share its Barbican stage. In addition to being one of the world's current top five, this orchestra has always led the way - with recordings, television tie-ins, film work and self-government by its players. They run their own record label, LSO Live (launched in 2000), and last year converted a Grade I-listed church, St Luke's, into a music-education centre. The orchastra's occasional woes have been no less dramatic, and it has had the narrowest squeak in musical history - as the first European orchestra to cross the Atlantic, it was prevented by a booking mix-up from travelling on the maiden voyage of the Titanic.
Ever since the London Philharmonic naively bared its communal soul to a journalist in the mid-Nineties- the revelations about sex, drugs and despair were so mortifying that many players couldn't face their colleagues on publication day - British orchestras have worried about their image, the periodically strife-torn LSO more than most. So it's with no expectation of lurid gossip that I hover backstage at the Barbican as they gather for their first public onslaught on Verdi's last opera. These ace professionals are famed for getting on with the job: they come, play and go home to partners and kids, usually without even a detour to the pub. But we can at least take the temperature, and see what makes them tick.
And also where they come from. Some players - such as the clarinettist Andrew Marriner - hail from musical dynasties, but the violinist Warwick Hill's beginnings in Barnsley could not have been humbler: "I noticed there was a school orchestra that met every Wednesday and said I'd like to be in it. An uncle bought me a violin, and my first teacher was a miner."
The tuba player Patrick Harrild's start was entirely accidental: "I played tuba in the brass band at school, and when I was 15 I did a Brahms lullaby - very badly - at a concert. The next day I got a call from a professor of the Royal Academy saying he wanted me to study with him. As I didn't know about the existence of the Royal Academy of Music, I thought it was the art one, so I said, 'I can't even draw, let alone paint.' My first lesson with him was a disaster, and I really only became a musician to vindicate myself."
While Harrild warms up his tuba, the trumpeter Maurice Murphy looks back over an astonishingly smooth career. This began when he was six, playing cornet next to his father, who was principal cornet of the Salvation Army in Stanley, Co Durham. He played contests, moved to a series of colliery bands and then to a works band, then the Fairey Aviation band, and then to Black Dyke when he was 20. "I had my last lesson when I was 12." After freelancing with orchestras all over the North, including spa orchestras - "Very good experience, as you had to double for lots of other instruments, and learn to transpose" - Murphy got a job with one of the BBC orchestras, was invited to join the LSO in Mexico for a fortnight, and on the plane home was offered the post of principal trumpet.
"And I've been here ever since. The Saturday morning I started was the first session for Star Wars. It seemed nice music, but none of us really knew what it was." What it was, of course, was the start of the LSO's most dependable money-spinner: as the film composer John Williams's orchestra of choice, they're booked to record for the sixth Star Wars film next February. Now they do sessions galore: what was the one they recorded yesterday? "I've no idea. Just some light music. A nice chap came with his arrangements and played them on the piano, to make a CD of some sort. I've forgotten his name. That's the pleasure of this job." Are there stresses too? "Well, you are exposed." Has he ever had an alarming moment? A beaming smile: "Can't remember one."
But we all rewrite history: a couple of days later, dipping into a company portrait that was published to mark the LSO's 80th anniversary, I discover that Maurice Murphy did once suffer an alarming loss of nerve that briefly but publicly ruined his playing. He'd been working too hard, and the pressure had affected his embouchure, which he'd signalled by cracking a note in that cruelly exposed lone trumpet call that opens Mahler's Fifth. Being the pro he is, he recovered his form within a couple of weeks.
Stress? In contrast to those poor saps in the LPO, nobody in the LSO seems to take beta-blockers, but the topic still crops up in this miasma of pre-concert tuning and practising that swirls round our heads. The violinist Nigel Broadbent's testimony is illuminating: "It's a funny thing, nerves. You can be feeling fine, then all it takes is one split second, where you expect to come in on a quiet entry, and you suddenly realise that nobody is coming in, and there's that extra gap, and you have to put your bow on very lightly... that's where it happens. An adrenalin shot - and you don't have the chance to burn the chemicals which are now flooding into the bloodstream. That's why it's good to go for a run afterwards. I've just joined a gym."
Brass players are not the only people at risk, Broadbent says: everybody has their exposed moments. "It's all a matter of muscular balance and relaxation. Even world-class weightlifters have this problem: they can't pull their best when they're nervous, because they have to relax the muscles that work in the opposite direction from the one they are pulling in. I've often heard top violinists getting ready for a concerto, going shift-shift-shift up and down the fingerboard in their dressing room, so that when they go on stage and nerves kick in, it still feels the same."
It was stress that impelled Warwick Hill to move down to the No 2 seat after 19 years as principal second violin. "I'd just had enough of leading. You have to wield the stick, but as this is a democratic orchestra, you can't do that heavily. You have to sort out bowings, and smooth the way between conductors and the other players. I wanted a less stressful life."
Regina Beukes left a principal's job in another orchestra to join the LSO as a rank-and-file viola. "It's lovely to leave the decisions to somebody else, to just sit back and watch things unfold, to let somebody else decide if it's an up or a down stroke." Why is that decision so important? "It reflects your interpretation of a phrase. It comes from the leader, down to the rest of the section." How easy is it to get out of kilter? "Experienced people acquire a sort of radar system: they react to each other very quickly. If I'm going to walk into a trap, my neighbour will help me not to. When you play with younger, less experienced people, you immediately feel the lack of this radar. They can walk into a wall quite easily."
Where you sit determines what you earn: the top four numbered desks in the first violins are on a sliding scale above the other 16 unnumbered players, who all earn the same, however long they've been here. But, as Harrild points out, some actually prefer to stay "rank and file". He says: "One musician, who's regarded as the absolute doyen of orchestral violinists, wouldn't dream of moving up. He loves being in the middle of the section. People tell me that when they sit next to him, they feel like better players."
That's another thing about this orchestra: they all move around, so nobody gets stuck in a bad position - next to the piercing piccolos or ear-bashing timpani, for instance. This constant movement also allows every player to assess those who join them on trial. Hundreds of hopefuls apply when a post falls vacant, and a musician can spend years on trial.
A statuesque young Pole, Iwona Muszynska, has just entered this process, and is learning to appreciate the collegiate ethos. "Poles are all trained as soloists, not as orchestral musicians. That means that everybody there is trying to be the best, the loudest, the most wonderful player. And it doesn't work, because an orchestra must be one organism."
After the performance and the tumultuous applause, Colin Davis pinpoints the key change in this band over the four decades he has known it: the influx of women. "They're very good players, and they make a different sound. The all-male orchestra was very efficient, but its sound was hard. It isn't any less efficient now, but the sound is softer and sweeter. The women don't play as aggressively, and they're more flexible - maybe because they don't put so much tension into it. They don't have such big hands, and they're not muscular unless they decide to be. They therefore remain very nimble. And with them, the men behave better. Nobody would dare to be drunk on the platform now."
How times have changed. When the LSO was conceived, a West End pub nicknamed the "Glue Pot' was the hub and recruiting office for London's musical life. Alcohol was the lubricant for everything. And the reason the LSO was conceived was paradoxical. With theatres, music halls and hotels all competing for the best players, it became customary to call in a friend to deputise if you suddenly got a more lucrative opportunity. Sir Henry Wood recalled that at one Prom he found himself facing "an orchestra with 70 or 80 unknown faces in it. Even my leader was missing."
Wood decided to demand loyalty from his players, but could guarantee them only £100 a year. Determined to keep their right to sell their services to the highest bidder, his top musicians resigned and, in 1904, set up "something akin to a musical republic", which they named the London Symphony Orchestra. Yet their prospectus implied that there would be no skiving off to better-paid gigs: it boldly asserted that they would be "second to none" among Europe's top orchestras.
And that's what they quickly became. Mahler himself was turned down when he offered to conduct them in 1907; Edward Elgar, briefly their principal conductor, was unceremoniously dropped when they decided he wasn't a big enough box-office draw (they gratefully received him back later on). They had to stay solvent, and did so by playing for choral societies and festivals, on tours abroad, and through working for a new-fangled medium called the gramophone.
The First World War's effect on concert life hit them hard, as did the slump in the early Thirties. The emergence of rival orchestras - including those of the BBC - further tested their ability to survive. Setting up the London Philharmonic, Thomas Beecham almost succeeded in wiping out the LSO for good, and work at newly established Glyndebourne opera was one of the LSO's saving perks.
In the Second World War, when 60 of their players were on active service, the old deputy system was needed again, and they toured tirelessly during the Blitz. The creation of the Arts Council promised a lifeline, but was also a threat to their cherished independence: they eventually bent the knee and got their grant, but its size meant they had to play endless games with other sponsors to stay afloat.
Zubin Mehta and Leonard Bernstein were among the glittering stars who conducted them in the Sixties, and when André Previn took over as principal conductor in 1968 - and BBC television started broadcasting André Previn's Music Night - the LSO became the height of cool. Claudio Abbado, who succeeded Previn, took the orchestra back to the intellectual high ground. But when they moved into the brand-new Barbican as its resident orchestra, financial calamity nearly zapped them again. The man who saved them - and who's still the managing director 20 years on - was a cellist drawn from their ranks, Clive Gillinson. "It was lucky I knew so little about the challenges of the job," he says. "Otherwise I'd never have taken it on." Yet, as Richard Morrison observes in his new history of the LSO, it's now become "the Manchester United of British music: a brand so big and powerful that it has no real competitors in its own country". Some of its principals - whose half-time contracts allow them to pursue parallel careers - are top-flight soloists in their own right.
LSO Live is an increasingly prominent part of this brand, with critical and commercial hits such as Colin Davis's inspirational recording of Berlioz's Les Troyens, and its budget-price CDs causing problems for the ailing big labels. But the LSO's bold conversion of an 18th-century church into the St Luke's music education centre - a key element in its strategy to cultivate future audiences - has put the orchestra once more into deficit, necessitating, among other things, a whip-round of £300 per head from the players themselves (that's the downside of owning your own company).
On the other hand, the LSO's City of London backing makes the other London bands green with envy. Gillinson replies that this orchestra does more London concerts than they do, and that City support only puts it on a par with leading regional bands like the Hallé in Manchester and the City of Birmingham Symphony Orchestra. Money is a problem that will never go away.
Meanwhile, Sir Colin Davis - now 76 and at the peak of his powers - leads his 110-piece band serenely on, secure in his conviction that orchestral music is one of the supreme inventions of the human mind. "I just wish our philistine government would take a pride in this orchestra's achievement," he growls. He points out a political moral: "This is a very small kingdom, and I can know everyone in it, and how they function. A prime minister is barred from that: he and his government sit in their offices, dealing with paper. An orchestra can vote you out tomorrow, if they decide you're intolerable. Very different from our elected tyrannies." Yes, indeed.
BATTLE OF THE BANDS: THE LSO'S RIVALS
BBC Scottish Symphony Orchestra
Under Martyn Brabbins, the Finnish conductor Osmo Vanska and now the young Israeli conductor Ilan Volkov, the BBC Scottish have made their name with adventurous programming and a willingness to go into uncharted territory in the recording studio, chiefly for the Hyperion label, with, for example, archaeological digs into long-lost Victorian British masterpieces.
Royal Liverpool Philharmonic Orchestra
The RLPO's music director, Gerard Schwarz, has come under fire in recent months for programming new and unfamiliar works such as Max Bruch's The Song of the Bell. At a meeting of musicians last month, more than half of them objected to Schwarz's five-year contract being extended. But nobody questions his musicianship, and his vision continues to gain critical approval.
BBC Symphony Orchestra
The orchestra rose to prominence under the baton of the arch-modernist Pierre Boulez, but has not had such a happy time of it since Sir Andrew Davis headed off to the Lyric Opera of Chicago in 2000. But it is still a formidable musical force, and its Composer Portrait series has brought much unusual work into the public eye, throwing new light on composers as varied as Kurt Weill, Harrison Birtwistle and John Cage.
City of Birmingham Symphony Orchestra
Sir Simon Rattle may have gone on to Berlin, but fears that his former orchestra would face a steep decline have proved unfounded. Its partnership with the starry Finnish musician Sakari Oramo, who became principal conductor in 1998 and music director in 1999, continues to generate heat with inspired performances of the Scandinavian repertoire.
Not to be outdone by the LSO, the Hallé launched its own record label in 2003 with three recordings. Conducted by the music director Mark Elder, these focused on works by Nielsen and Elgar, whose First Symphony was premiered by the Hallé in December 1908. This is an orchestra that has declined since its glory days, but it could be springing back.
LSO Gala, Barbican, London EC2 (020-7638 8891), 7.30pm, Wednesday. Richard Morrison's 'Orchestra: The LSO - a century of triumph and turbulence' is published by Faber and Faber (£20)Reuse content