As Rob Reiner, Michael McKean, Christopher Guest and Harry Shearer stood on the stage of New York’s Beacon Theater, basking in waves of deafening applause from their rabid sold-out crowd, one might have forgotten that their masterpiece began as a failure.

There was a palpable undercurrent of “look how far we’ve come” to last night’s grand salute to This Is Spinal Tap at the Tribeca film festival. Reiner, a skilled deadpan, knew to underplay it; walking out after the screening, he chuckled: “I haven’t seen this in twenty-five years. It’s pretty funny!” It’s been thirty-five years in total since its less-than-lucrative original release, and the stupidly clever (or is it cleverly stupid?) rock mockumentary can pack a tony Manhattan concert hall, the sort of gig that the fictitious Brit rockers would have once killed for. But the team of gifted comedians that put together an almost purely improvisational classic remember it as it began.

“The first time we screened the film in Dallas,” Reiner reminisced, “they asked us why we’d make a movie about a band no one had ever heard of, and one that’s so bad. And it was a good question.” Guest jumped in, adding: “Michael and I went to get some popcorn at the Dallas screening, and we heard two girls at the counter saying, ‘These guys are so stupid.’ They were right!” The early days of This Is Spinal Tap sound like the early days of Spinal Tap itself, as a group of idiot-savant visionaries brought their vision to a world not quite prepared for it. Shearer’s best anecdote took the temperature of the initial reception.

“Some of the response cards we got from audiences at test screenings were amazing,” he remembered. “There was one – I happen to know she was a woman, though that’s not the point – but under the section where you write what you liked about it, she wrote ‘DNA.’ How would you recommend this film to others, she wrote ‘DNA.’ We eventually figured out that that meant ‘Does Not Apply’.” Another respondent had noted that their favorite thing about the film was that it played in color.

This Is Spinal Tap. Photograph: Pete Cronin/Redferns

But the quartet of performers have gotten the last laugh, and it’s the kind of lung-filling belly laugh that only this film can provide. This Is Spinal Tap has transcended its second life as a cult sensation and fully permeated the mainstream, to the point that every office-party yutz can recite the “this one goes to eleven” scene verbatim from memory. The crowd telegraphed their knowledge of the film’s every beat and rhythm, bursting into Beatlemania screams with each cameo and one-liner. “None more black” went over like the chorus to I Wanna Hold Your Hand.

When Reiner made mention of an original cut running seven hours, including three hours of nothing but faux-interview riffing, the cheer in response suggested that they would be more than happy to watch it. A memory about a scrapped storyline involving The Runaways’ Cherie Currie giving the entire band herpes may be niche trivia elsewhere, but last night, it cast a spell over the silently rapt audience. A passing mention of seminal English rock outfit Saxon was enough to draw a swell of hoots in acknowledgement. McKean put his finger on the electricity in the room, identifying it as an reactive charge uncommon at the cinema. “Your reactions are concert reactions! You see a scene beginning, and treat it like it’s the beginning of ‘Free Bird’.”

And that was before they actually started shredding. After they had taken questions from their adoring public, McKean, Guest and Shearer whipped the house into a frenzy by picking up acoustic guitars and running through the film’s greatest hits. The past few decades have greyed the actors up a bit, but their voices haven’t aged a day, each part of their harmonies perfectly in place. From the flower-power anthems to the heavy metal lixx, the crowd knew every word – a poetic if unexpected fate for the band once forced to open for a puppet show.

This Is Spinal Tap is in part a paean to pop culture’s losers, to artists intent on doing their own thing no matter who it alienates. The film makes its subjects into the constant butt of mockery, but reserves a genuine affection for the characters as lovable underdogs trapped in a world that just doesn’t get it. Reiner, Guest, McKean and Shearer have transcended this narrative into which it once seemed like they had snugly fit, Spinal Tap’s humiliating lack of stardom eventually making the men playing them into stars. Posterity has recast them as the triumphant winners, shaping film history on their own sophomoric terms. Reiner seemed genuinely tickled that footage of him and his friends goofing around has been enshrined in the National Film Registry. Like Vincent van Gogh (if he had stuffed a zucchini down his trousers to make himself look more well-endowed), genius unappreciated in its time has at last been recognized.