Coca-Cola’s television ad featuring the infectious “I’d Like to Buy the World a Coke” and considered by many to be “the world’s most famous ad,” first took America by storm in 1971. Last May, it filled American homes once more as the finale scene in AMC’s long-running “Mad Men.” But, popular as the show was, Don Draper didn’t write that jingle. Its true author was Bill Backer, who died Friday in Warrantor, Va., at 89.

In the commercial, a camera pans across faces of all shapes, colors and ethnicities, as they sing from a hilltop in Manziana, Italy, “I’d like to buy the world a Coke.” When the ad was produced in 1971, it cost $250,000, making it the world’s most expensive commercial at the time, the Daily Beast reported. Which makes it all the more astounding that Backer came up with the idea while sitting in an airport cafe in Shannon, Ireland after his plane was forced to land due to a blanket of fog smothering London like pea soup.

At the time, Backer was the creative director on the Coca-Cola account for McCann Erickson, a global advertising agency. When he was grounded in Ireland, he had been en route to London to meet with the account’s music director Billy Davis. The two, alongside songwriters Roger Cook and Roger Greenaway, were to come up with some radio commercials for Coke. Some of the music was already written, but the lyrics remained elusive.

Instead of writing in a studio, though, Backer found himself among Brits and tourists, frustrated and angry at their delay. He was forced to spend the night in Shannon. In the light of morning, some of those passengers appeared happier. Heck, some were even sitting in the airport’s cafe and laughing at their shared misfortune, between gulps of bubbly Coca-Cola straight from the bottle. He later wrote of the scene:

In that moment [I] saw a bottle of Coke in a whole new light … [I] began to see a bottle of Coca-Cola as more than a drink that refreshed a hundred million people a day in almost every corner of the globe. So [I] began to see the familiar words, ‘Let’s have a Coke,’ as more than an invitation to pause for refreshment. They were actually a subtle way of saying, ‘Let’s keep each other company for a little while.’ And [I] knew they were being said all over the world as [I] sat there in Ireland. So that was the basic idea: to see Coke not as it was originally designed to be — a liquid refresher — but as a tiny bit of commonality between all peoples, a universally liked formula that would help to keep them company for a few minutes.

During an interview with Slate following the “Mad Men” finale, Backer remembered watching the laughing imbibers and writing on the back of a napkin, “I’ve got to teach the world to sing. I’d like to buy the world a home and furnish it with love” i.e. the groundwork for the jingle’s lyrics:

I’d like to buy the world a home and furnish it with love,

Grow apple trees and honey bees, and snow white turtle doves.

I’d like to teach the world to sing in perfect harmony,

I’d like to buy the world a Coke and keep it company.

[Repeat the last two lines, and in the background:]

It’s the real thing, Coke is what the world wants today.

“That’s what the product was doing at the time,” Backer said. “It just felt like I heard a voice from somewhere saying, ‘I’d like to be able to do this for the whole world.'”

The song hit radio stations on Feb. 12, 1971, and it gained immediate popularity. DJs immediately began receiving calls asking them to play the jingle, as if it were a song by The Doors or the Jackson 5. It was so popular, it began to affect the pop charts. The Hillside Singers had recorded the original vocals, and that version peaked at number 13. Backer had the New Seekers record a slightly different version of the song, titled “I’d Like to Teach the World to Sing (In Perfect Harmony),” which peaked at number 7 on the Billboard Hot 100, according to Billboard.

Given its popularity, the company decided to film a commercial using the jingle, hiring five hundred people from Rome to stand on the hilltop in Manziana and lip-sync the lyrics. Rain and other delays kept Backer and his team from hitting their initial budget of $100,000, but the soda company trusted his vision so thoroughly, it eventually shelled out $250,000.

They were likely glad they did. According to Coca-Cola, the company and its bottlers received more than 100,000 letters about it.

“It’s generally considered the world’s most popular commercial,” Backer said.

Roger Greenaway, one of the musicians who helped write the jingle, said he thinks it’s popularity came from a feeling of hope during a dark period in the country’s history.

“I think it was the flower power era, and most of America was tiring of the Vietnam War,” Greenaway told the ASCAP. “The lyrics, although not overtly anti-war, delivered a message of peace and camaraderie.”

That connection was something Backer looked for in his work. To Backer, it was the customer, not the client, who mattered most.

“I worked very hard, and I always imagined that I was talking directly to the public,” Backer said. “To the consumer. A lot of people were just trying to please the client. I never did that. I always imagined that I was sitting and talking to you directly.”