The line is not one you can easily ascribe to the composer of the 1812 Overture. “You be my cossack,” whispers a youthful Piotr Tchaikovsky as his friend Alexei drops to his knees in the quiet of a St Petersburg park at sunset. The light dims, the composer gasps his contentment, and only the judicious fade-in of a waltz from The Sleeping Beauty is there to spare our blushes.

But if we’re blushing at Tchaikovsky’s lustful indiscretions, then at least we’re not sobbing for his tortured soul. And that appears to be the main message from the Beeb when it broadcasts a two-part drama documentary fronted by Charles Hazlewood and starring Ed Stoppard in the title role. It isn’t just the highlight of the BBC’s unprecedented Tchaikovsky Experience, which starts on Sunday with a televised broadcast of Swan Lake, and culminates with the broadcast of the complete works of both Tchaikovsky and his modernist successor Stravinsky. It’s also a corrective to the perception of the composer as the fatalistic artist. Namely, that much of it is hokum.

Blame ideology. First, the Soviets, who systematically airbrushed out the composer’s homosexuality — clearly intimated both by him, his family and his friends at the time — but then by us decadent Westerners, who ramped it up at the expense of nearly every other aspect of Tchaikovsky’s personality.

The result was that the more the Soviet regime fêted Tchaikovsky as the standard-bearer of Russian culture, the more the opposing image — Tchaikovsky as the tortured gay loner, etching his internal conflicts on his compositions — was exaggerated. And with the break-up of the Soviet Union (and the publication of Tchaikovsky’s personal correspondence) it was this second image that seized hold.

Suzy Klein, the producer of the new biopic, says: “For a long time now there’s been a strand of musicology that said ‘Tchaikovsky is gay, and you can hear the gay pathology in his music’. It probably didn’t do gay musicians any good and it didn’t do Tchaikovsky much good.”

But if Klein holds little truck with that school of thinking (one noted Tchaikovsky scholar has defined his final symphony, the Pathétique, “a despairing homoerotic narrative”), she isn’t afraid to delve just as far into the composer’s sexual mores.

“We’re not trying to make a period Queer as Folk,” she insists, “but he was a very, very promiscuous man. He had very clear ideas about the kind of sexual relationships he wanted to have. He wasn’t remotely reserved or guilty about it.”

It’s not clear whether the meticulous research that Klein says is the foundation of the documentary extends as far as the film’s numerous clinches — on a train, in the park, in the sauna — as Stoppard cheerfully admits. “I don’t know if there’s documentary evidence where Tchaikovsky says: ‘Continued work on Fourth Symphony. Went to steam room’. Probably not. But the issue is not ‘Did he have sex with men?’ It’s about how he responded to his nature.”

As Klein explains: “If you don’t understand his promiscuity and relaxed attitude to who he was you don’t understand how much he’s giving up to get married.”

That aborted marriage certainly makes for one of the most tantalising (and misunderstood) episodes in the composer’s life. In the midst of composing the opera Eugene Onegin, in which the young and naive country girl Tatiana writes a letter declaring her love for the older and far more urbane hero, Tchaikovsky received a letter of his own, from an equally besotted admirer, Antonina Milyukova. Unlike Onegin, Tchaikovsky’s response was favourable. Within three months the marriage (never consummated) had collapsed, and the composer fled Russia.

Had the whole episode been a desperate bid to deny his own nature? Did it set up the kind of internal conflicts that musicologists have discovered in such dense works as the Manfred Symphony and the Hamlet Overture, the Fifth Symphony and even the half real, half fantastical world of Swan Lake? The BBC drama makes a more convincing argument: as a middle-class artist in a circle of leisurely aristocrats, Tchaikovsky’s professional reputation was considerably more vulnerable than theirs were and he felt he needed to take evasive action.

“Where Tchaikovsky feels he has to behave well,” says Klein, “they feel they can be flamboyant. His first thought was to protect his music and those around him didn’t really understand why he had to do that.”

It’s a narrative that carries far more weight than the image of an unstable Slavic soul. And it’s put into perfect relief by Stoppard’s canny portrayal, which gives us both Tchaikovsky the impulsive hedonist and Tchaikovsky the earnest craftsman. “I can never be ardent for anyone,” he stutters in the painfully embarrassing scene in which Tchaikovsky proposes to Antonina; his subsequent look of doom at the wedding, played out to the grinding climaxes of the Fourth Symphony — composed just before the disastrous liaison — is crushingly realistic, while his subsequent frolics with the young violinist Joseph Kotek show just how ardent he really was.

But if the marriage was a misguided attempt at selfdiscipline, Tchaikovsky remained a ruthlessly disciplined worker throughout his life, as capable of crafting the immaculate scores to The Sleeping Beauty and The Nutcracker as his more dramatic work for the concert hall. “Yes, he wrote alluringly seductive melodies,” says Klein, “but underneath the surfaces are huge amounts of thought, planning and craft.”

What solved the conflict between the man and his career was Tchaikovsky’s guardian angel, his patron Nadezhda von Meck. She emerged at the most pivotal period of his life, in the wake of his marriage. And her simple conditions? That he work consistently, and that they never meet. “They provided each other with exactly what the other needed,” Stoppard says.

Even when that relationship came to an end — she severed her contact with Tchaikovsky just as suddenly as she had started it — there’s little reason to think that the last years of his life were saturated in the gloom of that final symphony, the Pathétique.

Anyone hoping to see the composer’s suicide set to the strains of that symphony will be disappointed; Klein’s programme ignores the conspiracy theories that the composer took his own life out of shame. Banished are any theories that Tchaikovsky deliberately drank infected water. What lingers instead is the positive. As he lies on his deathbed, his brother Modest tells him: “You found yourself.” The reply is as moving as it is apposite: “No, I found music.”

Framed like this, the tragedy is not that Tchaikovsky found life unbearable, but that a man who lived it so fully came to such an untimely end at 53. “This is hopelessly romantic on my part,” confesses Stoppard, “but I liked him most when he was the young dynamic artist, wrapped up in all his clothes, with two lumps of coal left, composing. I love that image above all — and, yes, that’s the fumble-in-the-park era.”

Tchaikovsky: The Creation of Greatness, BBC Two, Jan 27 and Feb 3. Radio 3 broadcasts the complete works of Tchaikovsky and Stravinsky Feb 10-16. bbc.co.uk/tchaikovsky