"I said, 'You can play the beginning, or just the middle or the end, or none of it, but I'm not going to edit it," Webb recalled. KHJ began playing the full version.
"Once KHJ went on it," Tuna said, "everyone else went on it."
Webb says Beatles producer George Martin told him that "MacArthur Park" influenced the Beatles' decision to let "Hey Jude" run beyond the 7-minute mark when they recorded it a couple of months after Harris' record became a hit.
Now, half a century down the line, the composer believes the world is ready to hear it at least one more time.
"I have it on my new record coming out in September," Webb said, noting that his recording for his new "Still Within the Sound of My Voice" album due Sept. 10 features a vocal arrangement by one of his musical heroes, Beach Boys creative leader Brian Wilson.
Music was a big part of Webb's life growing up. His father was a Baptist minister and his mother played piano and accordion. The family moved to Southern California in 1962, settling in Colton in San Bernardino County.
"I can remember all the sprinklers going on all the lawns and the air conditioners humming and the sound of the Beach Boys floating from house to house," he said. "That was my first impression of California: sprinklers, air conditioning and the Beach Boys."
Three years later, his father decided to move the family back to Oklahoma. Just 17, Webb decided he was ready to be on his own, so he stayed.
"I had 30 or 40 songs I'd written, and I was ready," Webb said. "So I moved into a little — the nomenclature would be 'dump' — in Silver Lake."
That's when he discovered MacArthur Park, the recreational expanse built in the 1880s as Westlake Park, renamed in 1942 in honor of World War II Gen. Douglas MacArthur. He'd stroll from Silver Lake down Sunset Boulevard, across Alvarado and enter the park from a side street.
"That was my refuge from poverty," he said. "It was a place where I met my girlfriend; where life evened out for a little while. When I was there, it wasn't so difficult to live. That may sound strange now, because I was really successful so very young. But I was also struggling. At 17 years old I was on the street in Los Angeles with nothing to trade for my daily bread. Nothing but songs."
Though Webb has penned plenty more songs since, the cryptic lyrics of "MacArthur Park" still make the song one of his best-known — and most puzzling. What exactly was he singing about?
"I was very much an observer of things, and that song incorporated almost everything I saw around me," Webb said. "The novelistic technique of including just enough detail to convince someone of the veracity of the tale that's being told is a common one in songwriting. Certainly that's at work in 'MacArthur Park': the old men playing checkers by the tree, there's the yellow cotton dress....
"I'd seen birthday cakes left out in the park. I didn't have to make anything up," he said, although Webb also was well-read enough to have been aware of poet W.H. Auden's famous comment that, "My face looked like a wedding cake left out in the rain."
"'MacArthur Park?'" he said. "I have no apologies. It's just had a kind of wild and wacky and, ultimately, I guess, a wonderful existence as a song," he said. "And it's still around all these years later."
For many music aficionados, as unlikely as its commercial success was, that's no accident.
"What it feels like to me is that, even though he was barely in his 20s, an entire lifetime of musical ideas came pouring out in this one piece," said David Leaf, who teaches pop songwriting at UCLA. "It was as if he had been holding himself back, waiting for his chance, and then the Richard Harris record gave him the opportunity to put it all together. I never tire of hearing it — the timeless melodic themes, the structure of the composition with the different sections, the shifting tempos, the lyrical imagery — it really is everything one could dream of in a song and a record."
Where: Levitt Pavilion L.A.-MacArthur Park, 2230 W. 6th St., Los Angeles
When: 8 p.m. Saturday; free concerts continue Thursdays through Sundays through Aug. 25 in MacArthur Park; also Wednesdays through Saturdays from June 21 through Aug. 24 at Levitt Pavilion, Pasadena.