Vocal heroes: Going out on a natural high: 'High and sweet and strong'. Tess Knighton on what England expects of her cathedral choirboys

'Nothing uplifts like the perfect treble.' So says one of the older and more reactionary canons in Joanna Trollope's The Choir, a tale of the battle to save the choir school of the fictional cathedral of Aldminster. The canon is, of course, speaking in a spiritual sense (no smutty doubles entendres please, boys), and there is no doubt that his statement pinpoints one of the main reasons why the Church, at least in this country, has continued to support the cathedral choir schools. Go into almost any British cathedral or into many of the Oxbridge college chapels at Evensong and hear those treble voices soar up into and echo round the vaulted ceilings and perpendicular-style columns and arches, lifting hearts and minds heavenwards. In the context of a liturgical service, the voice of the choirboy has, since at least the later Middle Ages, imparted an angelical quality - a unique and inspiring blend of purity and innocence - to the music of divine worship.

But exactly what is it about the quality of the treble voice that uplifts and moves us so? (Even those who never attend Evensong will have experienced something of the sensation listening to Aled Jones sing The Snowman or the 'Pie Jesu' from Andrew Lloyd Webber's Requiem, to name but two secularised examples.) Most immediately, of course, there is the intrinsic sound of the treble voice, so high in pitch, so pure in tone.

The vocal qualities most prized in the Middle Ages, when choirboys began to be trained musically, were precisely these: the voice should be 'high and sweet and strong'. The sound of boy trebles began to be exploited by composers of sacred polyphony towards the end of the 15th century, especially so in Tudor England. In English polyphony of the 16th century, the top line was often divided into two (treble and mean) with a tessitura (or pitch level) that bordered on the vertiginous. The headmaster of the threatened choirschool at Aldminster refers to this tradition in his eloquent plea to save his institution: 'Without the choir of boys' voices that particular sound, a sound of unrivalled beauty and power, would not be possible. For 500 years, music has been composed to that top line of extraordinary sound and it is in English cathedrals alone that it remains, still uncorrupted, strong and free, with a higher standard of voice being recruited every year.'

Trollope is right to allude to the length and strength of the English cathedral tradition; certainly it is unrivalled in the rest of Europe, although there are famous boys' choirs in, for example, Vienna or the Benedictine monastery of Montserrat in Catalonia. However, even the English tradition has had its ups and downs with standards and morale reaching a dangerously low ebb at the beginning of this century. Then began an extraordinary revival with the injection of new levels of musical discipline at certain establishments, notably at King's College, Cambridge, under the direction of Boris Ord. And it was perhaps this choir, more than any other, that led the way, most publicly through the Festival of Nine Lessons and Carols broadcast each Christmas, with a sound that was pure (open-vowelled) and clean (precise in ensemble and intonation) and ethereal (perfectly suited to the reverberant acoustic of the college chapel).

Ord was succeeded by David Willcocks, who raised standards even higher and whose celebrated recording of Handel's Messiah had the trebles singing the soprano arias in unison. This has recently been digitally remastered, brought out on CD and reviewed in Gramophone, the critic remarking appositely that it 'successfully recaptures the unique King's College acoustic and all that goes with it. This is the Messiah of suede-silk boy soprano arias ('I know thett my Redeemer liveth, ent thett he shell stent . . .').' This hits the mark as regards both the interdependence of the tone quality of the boys and the acoustic of King's chapel (that kind of almost urgent breathing that sent whispers round the fan-vaulted ceiling) and also the precision and preciousness of the Willcocks approach, the sound being distinguished by the unanimity of those incredibly (almost forced) bright vowels and the emphatic togetherness of those final Ts. The sheer discipline of this approach, however, raised standards enormously - and not just at King's.

As a choirboy manquee in a mixed college chapel choir in the very shadow of King's, I, too, was trained to sing 'eck-shel-cees', with the bright vowels bringing out the upper partials of the harmonic series in a way that made the soprano line pure and milky and, well, boyish. The ramifications for the many excellent mixed professional 'early music' choirs were thus equally important.

The King's sound became the model for cathedral choirs everywhere, although not every choir director favoured its almost disembodied quality. For example, George Guest, further along the Cam at St John's College, adopted a more athletic approach to training his boys: 'To sing top notes,' he is quoted as saying in an article in Early Music in 1980, 'one needs to take big breaths, to throw one's shoulders back, and to adopt something of the poise of an all-in wrestler.' I have never noticed a resemblance between the boys of St John's and Big Daddy but it would be true to say that their sound has more punch, an almost hard-edged quality in comparison to the unalloyed sweetness of King's. Guest was just as strict a disciplinarian as Willcocks, but he perhaps concentrated less on vowels and more on the way in which the sound was produced. Interestingly, when he started out at St John's, he played recordings of Continental choirs to the boys in an effort to inspire them to a less distinctly English sound. 'Having established the sound,' he said in that interview, 'it is easy perpetuate it; boys are great imitators.' Guest also had a distinctive method of training the boys, making each chorister able to sing a three-octave range, from B flat or D below middle C to the G above top C, dispelling at a stroke the idea that notes in the top G or A range were 'high' (and so hard to reach). 'These notes do not have much practical value, except perhaps to reduce the terrors of the Allegri top C; but it also helps the boys here to have much bigger, more dramatic voices than most.'

This fuller, richer and often darker-hued sound is often described as 'Continental', although I do not think any serious analysis lies behind this. 'Non-King's' would perhaps be more accurate. The most distinctive of the boys' choirs is that of Westminster Cathedral, Roman Catholic and perhaps therefore with greater Continental affinities, but trained for most of the 1980s by David Hill, himself formerly an organ scholar at St John's. Under Hill's direction this choir enjoyed a tremendous boost of confidence, with a sound as rich and supple as any in the world, but as distinct from the vibrato-laden but equally striking sonority of the Escolania de Montserrat as from that of King's itself. Hill, now at Winchester Cathedral, where he has had a similar impact, clearly combined Guest's concentration on voice-training with the distinctive sound he inherited at Westminster. Their numerous recordings illustrate superbly how the boys bring a dramatically direct and full-blooded approach to the music of Continental composers such as Victoria and Palestrina: they are definitely my vocal heroes.

It is probably largely due to the experience of making recordings that standards have now reached unprecedented levels. But there is a downside to this extraordinary late 20th-century revival. Boys' voices are breaking earlier and earlier, and this means that inevitably a boy treble cannot normally achieve the degree of musical maturity and leadership of former times. The statistics are alarming: during the Renaissance, boys' voices did not break until the age of 17 or 18, and even up to World War II, it was common to find trebles 15 or 16 years old. Today, however, voices break at about 13, before most boys can possibly acquire much musical sophistication. And the reason? 'I blame McDonald's,' once said Gustav Leonhardt, co-director of Telefunken's complete Bach cantata cycle.

During the 20 years that project took to record, it became almost impossible to find a boy capable of singing a solo aria and so to re-create the kind of sound Bach himself would have had in mind. (There are, nevertheless, some extraordinary performances from members of the Tolzer Knabenchor.) It would appear, though, that modern protein-rich diets have brought about faster hormonal changes than of old; perhaps all boys with good voices should become vegetarians.

The banning of hamburgers would certainly be a mild threat compared to that faced by choirboy Hubert Anvil in Kingsley Amis's The Alteration. Castration is no longer deemed acceptable, thank goodness, even in the service of the papal choir. Amis finds the quality of the boy's singing voice 'resistant to definition, hidden somewhere among pairs of antonyms: full- grown yet fresh, under total control yet spontaneous, sweet yet powerful' (with these last adjectives he unwittingly echoes the medieval writers). Another pairing might be tradition versus transience: against a shadowy backdrop of centuries of trebles flickers the brief span of each boy chorister whose voice is lost along with his innocence (in medieval France the boy singers were referred to as 'les innocents'). Purity of sound gives way to a gruff and uncontrollable croak, native innocence is ousted by the desires of manhood. Thus the treble voice elicits from us a deep emotional response related to innocence lost and the transience of life - a universal image that Shakespeare (in As You like It) adapted to express, with the kind of poignancy evoked by that sound, the coming full circle from boyhood to senility: 'and his big manly voice, / Turning again towards childish treble, pipes / And whistles in his sound . . .'

(Photographs omitted)