‘Jack Flash sat on a candlestick’ … violence at a Rolling Stones concert at Altamont in 1969.

Who was the jester who sang for the king and queen in a coat he borrowed from James Dean? What exactly was revealed the day the music died? The Vietnam war, social revolution, Bob Dylan, Elvis Presley, JFK, Mick Jagger, Martin Luther King, Charles Manson, Hells Angels, The Beatles, hallucinogenic drugs, God, the Devil – they’re all in there, aren’t they? No one can be totally sure, except one man. There are fan websites dedicated entirely to decoding it. Every line of American Pie has been stripped bare. “Carly Simon’s still being coy about who You’re So Vain was written about,” he says. “Drove my Chevy to the levee but the levee was dry.” But McLean has always kept stumm about the allusions in his verses. There’s general agreement that the song is about the cultural and political decline of the US in the 1960s, a farewell to the American dream after the assassination of President Kennedy. That’s a lot of fuss for one song: McLean’s moment, perhaps, to tell the world once and for all what the lyrics actually mean. A Broadway show is planned for 2022, and even a children’s book.

McLean wrote it half a century ago, at the age of 24 – and to mark the anniversary, a new documentary, inevitably titled The Day the Music Died, will be released. The Recording Industry Association of America has the song in its top five, behind Over the Rainbow and White Christmas it’s been covered by everyone from Madonna to Tyson Fury, who sang it after knocking out Deontay Wilder earlier this year and the original handwritten lyrics sold in 2015 for $1.2m (£800,000), the third highest auction price ever for an American literary manuscript. We’re meeting, though, to talk about his era-spanning epic: that rollicking eight-and-a-half minute run-through of the 1960s after the decade closed. ‘The day the music died’ … the 1959 plane crash that killed Buddy Holly is thought to be one of the song’s references – but McLean hints it could be about his father’s death.

Meaning of american pie song