How often do you get to hear new music from a composer who’s been dead since 1791?

Not often, one suspects. And when the composer is Wolfgang Amadeus Mozart, the occasion is even more unlikely. The onetime child prodigy is possibly the most exhaustively studied musician in classical-music history. He’s been the subject of endless biographies, a Russian opera, and a Hollywood blockbuster, and he’s even had his supposed bones exhumed for DNA testing in an attempt to determine the real cause of his premature death, at 35. (The results were inconclusive.)

But it took a hot tip from a Mozart expert, and some forensic digging by a Vancouver composer, to determine that everybody’s been playing his Symphony No. 1 in E-Flat Major wrong. If the score generally followed for this short, charming composition sounds surprisingly mature for the work of an eight-year-old, that’s likely because it was subject to some harsh revisions at the hand of the prodigy’s father, Leopold.

The original is a wilder undertaking altogether, as former Calgary Philharmonic music director Hans Graf noticed while doing his own investigation into Mozart’s compositional genius.

“Hans has conducted my music a few times, so we were having drinks in Calgary and he was telling me about his very first job, as director of the Mozarteum [Orchestra] in Salzburg,” says Rodney Sharman, the musical sleuth who has restored the Symphony No. 1 to better match its youthful composer’s original intent. “He said there was so much music that he was overwhelmed, but he thought, ‘Okay, I’m an orchestra conductor; I’ll begin with the symphonies.’ And in the back of the urtext version of the collected works of Mozart is a facsimile of the first symphony. Hans said he saw all this invention—all these canons, all this play between the violas and the basses—and it’s all crossed out and the viola part just says ‘With the basses’. All of this eight-year-old’s imagination was being censored, was being taken away.”

When Sharman looked at the facsimile score, he noticed that two hands (and three pens) had been at work, but despite Leopold’s deletions he could still see Mozart’s original notes. That’s what we’ll hear during the Vancouver Symphony Orchestra’s 2015 Spring Festival, which this year is given over to the works of Mozart, the composers who inspired him, and the composers who followed him, as well as a screening of the aforementioned blockbuster, Amadeus.

Remarkably, Sharman’s restoration has only been played twice before—once in London, and once for a CBC broadcast.

“Rodney’s project was to try and read what Mozart wrote, as opposed to what Leopold wrote,” explains the VSO’s music director, Bramwell Tovey, reached in Harrogate, Yorkshire, where he’s leading workshops for the National Youth Brass Band of Great Britain. “And that, to me, makes it very interesting, because it’s a lot more wild and, in a sense, immature—but still indicative, perhaps, of the future man.

“The harmonies are not quite so staid, and some of the orchestration ideas are a little more youthful, as opposed to the whole score having the bloom of experience and maturity,” Tovey continues. “Which of course Mozart didn’t have. He was only eight years old, prodigiously gifted though he was.”

The conductor notes that while his music-detective alter ego, Inspector Tovey, will explore Mozart’s life in a child-friendly postfestival presentation on April 19, he’s much more interested in the mature Mozart, whose last three symphonies and subsequent Requiem are at the core of the VSO’s Spring Festival programming.

“If you ask the Inspector, who is with me here, he’s likely to say, ‘Wow, Mozart was pretty amazing. He was able to improvise at the piano with his eyes blindfolded; he was able to create variations on a theme that he’d only just seen; he was able to compose on the spot, without any kind of piano around, while he was playing billiards.’ Inspector Tovey, for the purposes of the kids, will find all of that quite impressive,” Tovey says. “But for me, it’s ‘Oh, yeah, it’s a big deal, but let’s look at the seriousness of the music and its legacy, which is amazing.’ ”

Tovey has a particular rapport with Mozart’s Symphony No. 39 in E-Flat Major: he conducted it for his graduation recital as a Royal Academy of Music student, and again in his debut with the New York Philharmonic. That initial foray, he confesses, is best forgotten: “I just remember it being very leaden and heavy. I think it was probably more like [Anton] Bruckner than Mozart.” But whenever he has returned to the work and its companion pieces, which were written in an intense burst of late-life inspiration, he’s found them to be more and more impressive.

“There’s certainly a tragedy and a pathos, as well as extraordinary joy, in the last three symphonies,” Tovey explains. “For me, the second movement of the 41st, the ‘Jupiter’ Symphony, is one of the most tragic things in all music. It’s extremely dark—darker even, I think, than the Requiem. But on the other hand, in the opening and the last movement of the 39th Symphony you just hear this sort of liberated joy.

“It’s just amazing how many different moods and how many different frames of mind there are in the course of just three works composed within six weeks,” he continues. “Yes, Mozart was a prodigy—but, my gosh, what an extraordinary mind he must have had to produce this wide cross-section of human emotion in just six weeks and have all three symphonies last in perpetuity. That, for me, is the genius of Mozart.”

The Vancouver Symphony Orchestra’s Spring Festival runs at the Orpheum from Friday (April 10) to April 18. Inspector Tovey Meets Mozart takes place at the Orpheum at 2 p.m. on April 19.