West Side Stories is a riveting reflection on the real lives that inspired the musical

But such soaring standards as America, Tonight and Maria came very close to never being heard. In this riveting documentary, Strictly judge Bruno Tonioli and arts broadcaster Suzy Klein discover real-life stories as exhilarating, moving and sad as the musical itself.

It was choreographer Jerome Robbins who came up with the idea for a musical updating of Romeo and Juliet in 1947. East Side Story, as it was then called, focused on the conflict between Catholics and Jews in Manhattan’s Lower East Side.

When the project eventually took flight on Broadway a decade later, it was Jets (a white gang) clashing with Sharks (Puerto Ricans), with a tragic love story at its core. And joining Robbins was a trio of artistic titans: Arthur Laurents (book), Leonard Bernstein (music) and Stephen Sondheim (lyrics).

West Side Story’s plea for tolerance chimes as much today as it did when discrimination and riots were rife in mid-50s New York.

Puerto-Rican actress Rita Morena, who played Anita in the 1961 film, recalls those racial tensions that inspired the musical. She and her mother left their country to live in the Big Apple but, she says, “It was not a happy welcome. People didn’t like us very much.”

With its cast of unknowns, fight scenes and three murders, West Side Story couldn’t have been a much riskier proposition. The memories of tense pre-debut rehearsals, and archive photos of the producers’ grim faces, sum up just how much was at stake. Rumble scenes even ended in blood and breakages.

Venerated wordsmith Stephen Sondheim, then only 25, recalls his niggly relationship with genius composer Leonard Bernstein: “He was very fond of changing my lyrics. I would write something and he would change it and say, ‘Wouldn’t this be better?’ Then we would argue!”

He also remembers perfectionist choreographer and director Jerome Robbins altering Bernstein’s orchestration. “Lenny hated confrontation and Jerry knew that.”

But all the creative friction gave rise to a work of art, a musical for all times and a universal prayer. It’s a stupendous documentary.

West Side Stories: the Making of a Classic is on Boxing Day at 5.20pm on BBC2