Carly Simon unveils 'lost' verse from 'You're So Vain'

For the first time ever, Carly Simon performed the mysterious "lost" verse from her iconic hit "You're So Vain."

Though she had unveiled the actual lyrics from the song's unreleased fourth verse in her memoir in 2015, Simon had never sung the verse in public before she did so recently on BBC's new documentary, "Classic Albums."

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"This is a verse that I haven't ever sung," she says in the footage. "I wrote it a while ago on a pad, but it never made it into the song."

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BEVERLY HILLS, CA- OCTOBER 30: Singer Carly Simon arrives at the Oceana Partners Award Gala With Former Secretary Of State Hillary Rodham Clinton and HBO CEO Richard Plepler at Regent Beverly Wilshire Hotel on October 30, 2013 in Beverly Hills, California.(Photo by Jeffrey Mayer/WireImage)
BEVERLY HILLS, CA - OCTOBER 30: (L-R) Singer Carly Simon, actresses Jane Fonda and Melanie Griffith arrive at the Oceana Partners Award Gala at the Beverly Wilshire Hotel on October 30, 2013 in Beverly Hills, California. (Photo by Kevin Winter/Getty Images)
FOXBORO, MA - JULY 27: Carly Simon joined Taylor Swift backstage tonight at Gillette Stadium in Foxborough, Mass. in front of a sold-out crowd of more than 55,000 fans for a special duet performance of her iconic hit ÂYouÂre So Vain. (Photo by Theo Wargo/TAS/Getty Images for TAS)
HOLLYWOOD, CA - APRIL 18: Carly Simon speaks at the 2012 ASCAP Pop Awards - Show at Hollywood Renaissance Hotel on April 18, 2012 in Hollywood, California. (Photo by Jonathan Leibson/WireImage)
PHILADELPHIA, PA - MAY 10: Musician Carly Simon performs during the 2011 Marian Anderson award gala honoring Mia Farrow at the Kimmel Center for the Performing Arts on May 10, 2011 in Philadelphia, Pennsylvania. (Photo by Gilbert Carrasquillo/Getty Images)
GOOD MORNING AMERICA - Artist and author Carly Simon appears on GOOD MORNING AMERICA, 4/12/11 on the ABC Television Network. GM11 (Photo by Ida Mae Astute/ABC via Getty Images)
NEW YORK - APRIL 29: Musician Carly Simon performs onstage at the 'You're So Vain' after party during the 2010 Tribeca Film Festival at 1 Oak on April 29, 2010 in New York City. (Photo by Joe Corrigan/Getty Images for Tribeca Film Festival)
LONDON, ENGLAND - MARCH 02: ***EXCLUSIVE ACCESS*** Carly Simon performs exclusively for BBC Radio 2 at BBC Maida Vale Studios on March 2, 2010 in London, England. (Photo by Andy Sheppard/Redferns)
TV Personality Dick Cavett and Musician Carly Simon attend the Party to Celebrate Her Book 'The Nighttime Chauffeur' on October 14, 1993 at The Central Park Boathouse in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon, son Ben Taylor and Jenny Nichols (Mike Nichols' daughter) attend the 'Danny the Champion of the World' New York City Premiere Party on November 18, 1989 at Hard Rock Cafe in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the 37th Annual Grammy Awards on March 1, 1995 at Shrine Auditorium in Los Angeles, California. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the American Ballet Theatre's 1995 Sping Gala on May 1, 1995 at Metropolitan Opera House in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the Creative Coalition's Spotlight Award Honoring Robin Williams on October 16, 1995 at Pierre Hotel in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the 'Indochine' New York City Premiere on November 5, 1992 at Gotham Cinema in New York City. (Photo by Ron Galella/WireImage)
Musician Carly Simon attends The American Museum of the Moving Image Salute to Mike Nichols on February 27, 1990 at Waldorf-Astoria Hotel in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the 61st Annual Academy Awards on March 29, 1989 at Shrine Auditorium in Los Angeles, California. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the 'Sleight of Hand' Broadway Play Preview Performance on April 21, 1987 at Cort Theatre in New York City. (Photo by Ron Galella/WireImage)
Musician Carly Simon attends the Hereditary Disease Foundation Dinner/Dance Benefit Gala on February 2, 1987 at the Metropolitan Club in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends 'The Inquiry' New York City Premiere on February 10, 1987 at City Cinemas Cinema 3 in New York City. (Photo by Ron Galella, Ltd./WireImage)
Musician Carly Simon attends the 'About Faces' Benefit Exhibition of Celebrity Lifecasts by Willa Shalit on April 28, 1986 at The Lighthouse in New York City.
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"You're So Vain" was the first single from Simon's 1972 album No Secrets, which is ironic because the legendary singer has never revealed who the whole song is about. In 2015, she confirmed that the song's second verse is about Warren Beatty, though he's not the subject of the entire song.

"He thinks the whole thing is about him," she told People in 2015, before adding that its also about two other people.

The new fourth verse doesn't reveal any real clues into the mystery, but fits into the rest of the song nonetheless. Read the lyrics below:

A friend of yours revealed to me / That you loved me all the time / Kept it secret from your wives / You believed it was no crime / You called me once to ask me things / I couldn't quite divine / Maybe that's why I have tried to dismiss you, tried to dismiss you

Watch Carly Simon perform the lost "You're So Vain" verse here.

RELATED: See photos of Warren Beatty:

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American actor Warren Beatty (Henry Warren Beaty) kissing American actress Natalie Wood (Natalia Nikolaevna Zakharenko) in a scene from the film Splendor in the Grass. USA, 1961 (Photo by Mondadori Portfolio by Getty Images)
circa 1955: American actor Warren Beatty wears a white button-down shirt in his apartment. (Photo by Hulton Archive/Getty Images)
Joan Collins and Warren Beatty who are engaged. (Photo by Michael Ward/Getty Images)
Circa 1961, American actors Warren Beatty and Natalie Wood (1938 - 1981) look over their shoulders while seated together at a formal event. (Photo by Getty Images/Getty Images)
Warren Beatty during the festival in Cannes (Photo by Daniel Fallot/INA via Getty Images)
American actors Warren Beatty and Natalie Wood (1938 - 1981) at the Cannes Film Festival, France, 14th May 1962. (Photo by Silver Screen Collection/Getty Images)
circa 1965: American actor Warren Beatty smiling with his arm around British-born actor Joan Collins. Beatty is wearing a tuxedo. Collins is wearing a silk jacket with a high collar. (Photo by Hulton Archive/Getty Images)
American actor Warren Beatty, wearing a cardigan and glasses, portrayed outside the Excelsior Hotel while standing next to a woman holding a newspaper, Lido, Venice 1965. (Photo by Archivio Cameraphoto Epoche/Getty Images)
UNITED STATES - CIRCA 1965: Close-up of actor Warren Beatty in an unidentified movie, ca.1960s. (Photo by Camerique/Getty Images)
American actor Warren Beatty portrayed while sitting on a sail boat side on the Lido beach, in front of the Excelsior Hotel, Lido, Venice, 1956.(Photo by Archivio Cameraphoto Epoche/Getty Images)
UNITED STATES - CIRCA 1965: Close-up of actor Warren Beatty in an unidentified movie, ca.1960s. (Photo by Camerique/Getty Images)
UNITED STATES - CIRCA 1965: Close-up of actor Warren Beatty in an unidentified movie, ca.1960s. (Photo by Camerique/Getty Images)
American actor Warren Beatty in a promotional portrait for 'Kaleidoscope', directed by Jack Smight, 1966. (Photo by Silver Screen Collection/Getty Images)
American actor Warren Beatty as Clyde Barrow on the set of the crime drama 'Bonnie and Clyde', 1967. (Photo by Henry Gris/FPG/Getty Images)
American actor Warren Beatty as Clyde Barrow in 'Bonnie And Clyde', directed by Arthur Penn, 1967. (Photo by Silver Screen Collection/Getty Images)
Richard Burton, Guest, and Warren Beatty during 'A Flea in Her Ear' Paris Premiere in Paris, France, United States. (Photo by Ron Galella/WireImage)
UNITED STATES - CIRCA 1970: Scene showing Warren Beatty lying down next to Elizabeth Taylor, from the movie 'Only Game in Town', 1970. (Photo by Camerique/Getty Images)
Warren Beatty with Michael J. Pollard; circa 1970; New York. (Photo by Art Zelin/Getty Images)
Portrait series of actor Warren Beatty as he knots his necktie, late 1960s or early 1970s. (Photo by Jack Robinson/Hulton Archive/Getty Images)
Warren Beatty during International Film Importers of America - February 27, 1970 at Americana Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Warren Beatty and Goldie Hawn hold money in a scene from the film '$', 1971. (Photo by Columbia Pictures/Getty Images)
(GERMANY OUT) *30.03.1937-Schauspieler, Regisseur; USAin dem Film `Shampoo'Regie : Hal AshbyUSA 1975 (Photo by ullstein bild/ullstein bild via Getty Images)
Warren Beatty and Diane Keaton (Photo by Ron Galella/WireImage)
Warren Beatty (Photo by Tom Wargacki/WireImage)
Warren Beatty during National Association of Theater Owners Awards at Americana Hotel in New York City, New York, United States. (Photo by Ron Galella/WireImage)
Warren Beatty during Tri-Star Pictures Pre-Oscar Party at Chasen's Restaurant in Beverly Hills, California, United States. (Photo by Ron Galella/WireImage)
Warren Beatty during 49th Annual Golden Globe Awards at Beverly Hilton Hotel in Beverly Hills, California, United States. (Photo by Ron Galella/WireImage)
05/11/98 - The Four Seasons Hotel, NW DC Actor Warren Beatty, in town to promote his new film 'Bulworth', during interview with the Post. PHOTOG: Bill O'Leary/TWP. (Photo by Bill O'Leary/The Washington Post/Getty Images)
Warren Beatty & Annette Bening during 11th Annual AIDS Project Los Angeles 'Commitment to Life' Gala at Universal Amphitheatre in Universal City, California, United States. (Photo by SGranitz/WireImage)
Warren Beatty, recipient of the Millestone Award during The 15th Annual Producers Guild Awards - Show at Century Plaza Hotel in Los Angeles, Ca, United States. (Photo by L. Cohen/WireImage)
LOS ANGELES - JANUARY 17: Actors Annette Bening (left) and husband Warren Beatty pose at the 15th Annual Producers Guild Awards on January 17, 2004 at the Century Plaza Hotel, in Los Angeles, California. (Photo by Kevin Winter/Getty Images)
HOLLYWOOD - FEBRUARY 27: Actors Warren Beatty and wife Annette Bening attend the Governors Ball after the 77th Annual Academy Awards at The Highlands on February 27, 2005 in Hollywood, California. (Photo by Vince Bucci/Getty Images)
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