Carly Simon finally tells us who You're So Vain is really about.

He’s so vain he definitely thinks the entire song is about him.

Carly Simon has been singing about that impossibly vain moron she once dated for more than 40 years in her best-loved song You’re So Vain.

She’s always refused to name the egomaniac in question, but she’s dropped many a hint over the years.

Simon, 70, in an interview with People to promote her new memoir, Boys in the Trees, has said that actually, the second verse of her song is about her one-time lover actor Warren Beatty.

Of the self-absorbed lover, Simon sang, “You’re so vain, you probably think this song is about you.”

Here’s how the second verse goes:

You had me several years ago when I was still quite naive / Well you said that we made such a pretty pair / And that you would never leave / But you gave away the things you loved and one of them was me / I had some dreams, they were clouds in my coffee / Clouds in my coffee, and… [chorus]

Beatty always suspected as much and actually called Simon after the song was released to thank her for it.

Watch Carly Simon performing You’re So Vain in what’s got to be the 1980s… Post continues after video.

“Warren thinks the whole thing is about him!” says Simon.

Au contraire, Beatty. Actually, two other men are honoured in the song but Simon plans to keep their identities a secret, “at least until they know it’s about them.”

She’s had romantic entanglements with musicians including Kris Kristofferson, Cat Stevens, Jamse Taylor and Mick Jagger, who actually sings back-up on the song.

Would she ever tell the other two guys that they are so vain?

“Probably, if we were sitting over at dinner and I said: ‘Remember that time you walked into the party and…’,” she told People.

“I don’t know if I’ll do it. I never thought I would admit that it was more than one person!”