There’s actually only one type of music – that’s good music

Performers have always crossed over genres without hindrance, long before the category of ‘crossover’

The weather will mostly be fine at this year's festival, but some wet weather early next week could leave things a little damp. (Ian Gavan/Getty Images)

At next week’s Glastonbury Festival, visitors will not need to stir from the Pyramid Stage – where the headline acts play – if they want to catch an orchestra, complete with eminent classical conductor. The maverick maestro Charles Hazlewood will be bringing a 26-piece band to Worthy Farm to back the Northumbrian folk-based ensemble, The Unthanks.

Later, on the same stage, the Glasto masses can croon along with Burt Bacharach. That evergreen troubador studied with the legendary composition teacher Nadia Boulanger – who also taught, in addition to Leonard Bernstein and Philip Glass, Michael Jackson’s producer Quincy Jones. He also studied with the French modernist pioneer Darius Milhaud. “Never be afraid of something that is melodic and can be remembered,” Milhaud told Burt. He learnt that lesson well.

On the summer festival scene, such merry eclecticism has become almost the default setting. If you go down to the woods today, you’re as likely to stumble across a ballet troupe or a string quartet as a stand-up comedian. To anyone with halfway-open ears, the musical fences were trampled down long years ago. I say a little prayer that, one day, we may stop gawping at the endless cross-border traffic between different genres as if it was a freak event, and just walk on by instead.

Performers and audiences alike have always crossed over without hindrance, long before the music biz concocted the gloopy soup of “crossover” as a distinct commercial category. It’s now almost a century since, in 1919, Ernest Ansermet – the great Swiss conductor and avant-garde champion of Stravinsky and Prokofiev – heard Will Marion Cook’s Southern Syncopated Orchestra. In a landmark review, he lauded the jazz band’s “extraordinary clarinet virtuoso” Sidney Bechet, in whose solos Ansermet found “the germ of a new style”. Two decades later, Arnold Schoenberg, godfather of atonality, paid a heartfelt tribute to his buddy George Gershwin as an “innovator” and an “artist”. Praising the supreme pop-song composer of his time, Schoenberg insisted that “what he has done with rhythm, harmony and melody is not merely style”.

Yet, even now, any august institution that dares to remind us of the essential unity of music can expect to be either hailed or jeered as a reckless innovator. It’s not so much a case of déjà vu as da capo: once more, from the top. When the BBC Proms scheduled gigs next month to mark 20 years of Radio 1’s involvement in the Ibiza scene, and invited Pete Tong along to host, the programmers knew that they could depend on reflex headlines of the “Who’d have thought it?” sort. But the Proms gates opened wide almost half a century ago. The first “pop” group to play there took to the Albert Hall stage in August 1970: Soft Machine, Robert Wyatt and Kevin Ayers’ jazz-rock band.

Barriers do remain, some more logical than others. This weekend brings the finals of the BBC’s Cardiff Singer of the World competition. As is now habitual, the contest has found itself tucked away on BBC4. Why not BBC1? Beyond the format’s reality-show glitz, this year’s contestants have enough glamour and charisma to outshine a studio full of wannabe boy-bands. Besides, some Cardiff victors have not only conquered the opera houses but cast a vocal spell on a much wider public. Notably, bass baritone Bryn Terfel – winner of the Lieder Prize in 1989 – can be spotted singing his heart out for the Welsh rugby team or starring on Broadway with Emma Thompson (in Sondheim’s Sweeney Todd) as well as at Covent Garden, La Scala or the New York Met. Measured across all platforms and across decades, a Terfel will reach many more people, for much longer, than any of the acts so far thrown up by the BBC’s prime-time search-for-a-pop star vehicle, The Voice. Other Cardiff laureates – such as Finnish soprano Karita Mattila and Russian baritone Dmitri Hvorostovsky – rank among the best-loved classical singers of the past 30 years.

With operatic voices, the boundaries between “classical” and “popular” celebrity have often proved as threadbare as Mimi’s poor rags in a bog-standard production of Puccini’s La Bohème. Superstar status came to the great vocal powerhouses around a century before Luciano Pavarotti nailed “Nessun Dorma” to the 1990 World Cup and Freddie Mercury duetted into eternity with Montserrat Caballé. In 1951, the top-grossing film in Britain was The Great Caruso: a biopic of one operatic giant played by another, Mario Lanza – that turbocharged tenor who was much more than a middlebrow heart-throb.

Half a century before that, the opera divo or diva did not merely compete with the pop idols. They were the pop idols. From Enrico Caruso himself to John McCormack, Adelina Patti and Nellie Melba, these first authentic global stars – their voices spread around the planet by phonograph recordings – routinely mixed operatic arias with folk songs, popular ballads and favourite hymns.

The Caruso generation crossed over but they did not do “crossover”, that glutinous pap that has tempted some fine voices into the lucrative swamplands at the musical middle-of-the road. The peerless Franco Corelli – the Italian tenor whom the snootiest opera buffs will sometimes rate above Pavarotti, José Carreras or Placido Domingo – thought that young Andrea Bocelli had talent, and gave the sightless Tuscan singer lessons. “I am almost sure that without Corelli there would never have been Bocelli,” the latter has said. I’m not sure that even the big-hearted Corelli would have wholly approved of Bocelli’s recent duets with Jennifer Lopez and Nelly Furtado. To love various sorts of music does not mean hankering after some synthetic mash-up. The problem with “crossover” lies not so much with the quality of these platinum-selling voices as with the studio-driven urge to whisk up discrete genres into a flavourless aural smoothie.

John McCormack – friend of James Joyce, no mean light tenor himself – would respect the difference between a Mozart aria and a delicate Irish air even if, when he unleashes his silky purring beast of a voice on the latter, it can resemble a Rolls-Royce engine attached to a donkey-cart. In music, as in other arts, an open-minded pluralism that breaks down the artificial walls between forms and audiences need not lead to the bland soup of “fusion”.

So, to return to the BBC’s summer of music, something other than old-school snobbery drives the naming of the corporation’s current “classical voice” season on radio and television. Even in an age that applauds artistic interchange, there can be a value in keeping things separate. On the athletics track, the 100 and 10,000 metres call for distinctive temperaments and endowments. So it is with singing. Over the past century, the greatest single nursery of world-class female voices has surely been the African-American choral tradition. To the black churches we owe the first musical steps of Jessye Norman and Marian Anderson, Sarah Vaughan and Ella Fitzgerald, Kathleen Battle and Dinah Washington, Aretha Franklin and Whitney Houston. Yet, to pick two other daughters of the Southern congregations, one can love both Tina Turner and Leontyne Price without wishing that one sounded more like the other.

Not long ago I interviewed the gloriously gifted South African soprano Pumeza Matshikiza, who grew up in a poor township in the Cape, sang in school choirs and then, aged 14, first heard opera. On her album Voice of Hope, Pumeza switches between arias, African traditional songs and the township pop made internationally famous by Miriam Makeba. Each style calls for a specific technique. “With the operatic pieces you use your full voice, your full body… with African music, it’s more like something between the speaking voice and a crooning voice,” she said. For a recital that moves between Mozart and Makeba, “I always have to start with opera and finish with the South African music. It’s difficult to do it the other way.”

So begone, “popera”. Truly eclectic taste means attention to genuine variation in mood and method along with scorn for the phoney barriers erected by custom, prejudice or mere marketing convenience. With the implosion of the 20th-century music industry, that last obstacle should swiftly fall. The latest statistics from the recording-industry umbrella body IFPI reveal that digital media now generate 46 per cent of total revenues worldwide. Even within the disembodied sector, streaming services have overtaken downloads in 37 national markets. Scattered over an ever-wider landscape of outlets and devices, from the arena to the earplug, music now functions as what IFPI dubs “a portfolio business”. In this new flux, the old audience-slicing demarcations should feel as anachronistic as an audio cassette.

Farewell, let’s hope, to the defunct record-shop apartheid of different racks for different folks. The key requirement must be that consumers can discover the music they do not yet know but may adore once they do. Hence the value of Glastonbury, of Latitude, of the Proms: of any festival, venue or programme which springs an ear-opening surprise on its listeners. With luck, that unheralded exposure will mean more life-changing episodes to match the moment when Pumeza Matshikiza heard the Swiss Mozart specialist Edith Mathis on the radio. She thought: “That is just heavenly, out of this world… I would like to sing like that.” It was. She did.