The operas that made him, at 61, one of America’s most famous and prolific composers struggle with epic themes: Dead Man Walking (2000) and, with librettist Gene Scheer, Moby Dick (2010 ). But Heggie stuck with a favorite mantra.

“Aim big or go home,” he says. “I need to be terrified before starting a new project so that I don’t repeat myself. I thought of the classic stories that have this sense of the big but also of magic and redemption.

“All the things we yearn for on vacation,” he continues. “It just came to me. I didn’t realize how hard the choice was going to be – honor the source but do something different. My writing partner said it was harder than Moby Dick.

After persuading Paramount Pictures to hand over the rights, which took a few years, this challenge was to reshape a much-loved story with a fast-paced script that jumps from the 1920s to the 1940s, from heaven to earth; from darkness to light. Heggie and Scheer chose to focus on the story’s numinous idea “that there are angels who see the value in our lives if only we would pay attention”.

One unspoken influence was her own father’s suicide when Heggie, who grew up in a small town outside of Columbus, Ohio, was just 10 years old. “Of course I thought of my father,” he says. “But my dad suffered really deeply from a mental illness that they couldn’t treat. George [Bailey] is driven by despair and fear and feels very alone.

Prevented from living life on a larger canvas, George is an intricate portrait of small-town heroism. Circumstances prevent him from leaving for college, for his honeymoon, or for the war, unlike his brother Harry who returns as a hero. Unlike Stewart too: a decorated veteran of 20 outings in Europe, it was his first role in five years.

It’s quite a mantle to inherit for Frederick Ballentine, the American tenor who lit up the London Coliseum in 2018 playing drug-dealing pimp Sportin’ Life in Porgy and Bess. He had not seen the film. “I thought it had such a tradition in the States that I probably should know because I’m a good conservatory boy and I learn by example,” he says.

“Overall,” he adds regretfully, “it might have been up to me not to watch it. I guess there’s more levity [in the screen character]. It’s James Stewart, but is it an opera?