When his Broadway show became a global phenomenon, the rigours of daily performance kept the actor and songwriter grounded. Then Disney and Hollywood came calling. Now, the ‘musical theatre fanboy’ has returned to his first love

About halfway through Tick, Tick ... Boom!, the new movie directed by Lin-Manuel Miranda, the patrons of a diner in 90s New York all turn to the camera and sing. The movie, Miranda’s directorial debut, is based on the autobiographical stage show of the same name by Jonathan Larson (creator of Rent) and tells the story of Larson’s late 20s as a struggling writer and waiter. Andrew Garfield is extraordinary in the lead, but it’s the people around him who make this particular scene; as the number unfolds, it becomes apparent that every extra in the diner is a legend of musical theatre, from Bernadette Peters, to Brian Stokes Mitchell (a veteran Tony award winner), to Roger Bart (original cast, Tick, Tick ... Boom!), to Jim Nicola (former artistic director of the New York Theatre Workshop) to a blink-and-you’ll-miss-it shot of Joel Grey, chasing the waiter for the bill. “I don’t know that I’m the guy you hire to make your next Marvel movie,” Miranda says, speaking via video from his office in uptown New York, “but I am the guy you hire to make this musical about a guy who wrote musicals.” It is simultaneously funny, moving and monstrously self-indulgent – or, as Miranda puts it, “about as musical theatre nerdy as it can get.”

Imagining Miranda as the steward of an alternate Marvel universe – Comic-Con, but for musical theatre geeks – restores him to what, prior to the opening of Hamilton in 2015, was his quieter role in the cultural landscape: as the champion of a much-loved, much-mocked art form that rarely troubled mainstream popular culture. Hamilton changed all that. The show not only won 11 Tonys, a Pulitzer, and more than $850m in box office receipts, it conferred on Miranda a singular status, variously crediting the 41-year-old with reanimating history, diversifying Broadway, and provoking children all over the world to memorise large chunks of lyrics about America’s revolutionary politics, some of them concerned with the restructuring of the national debt. (“Hey yo, I’m just like my country / I’m young, scrappy and hungry / And I’m not throwing away my shot” – still being hammered out at a million barmitzvahs). The most surprising thing about all this, perhaps, is that Miranda, appearing today in his customary flat cap and goatee, has the boundless enthusiasm and apparent absence of cynicism of the aspiring artist still untouched by success.