Who's so vain? Carly slips world a new clue

It is one of the most enduring mysteries in music: who is the subject of Carly Simon's 1972 hit, 'You're So Vain'?

Now the singer has provoked further speculation by performing a "lost" fourth verse on a BBC documentary, in which she sings: "A friend of yours revealed to me / That you'd loved me all the time / Kept it secret from your wives / You believed it was no crime."

That reference to "wives" may rule out several contenders who were either unmarried or only on wife No1 when the song came out. They include Mick Jagger, Cat Stevens, Kris Kristofferson and David Geffen, the record mogul.

But it fits another man: Willie Donaldson, a British othario who was the first man to break Simon's heart, and who she described in her 2015 memoir as "a sardonic, adorable, long-legged, coffee-scented charmer" (coffee is mentioned in the lyrics of the song ).

Donaldson, the son of a shipping magnate, inherited and spent a fortune, smoked crack and at one point took up residence in a brothel in Chelsea, London . He was also the author of the Henry Root letters, a famous literary hoax in which he wrote to the great and the good, from Margaret Thatcher and the Archbishop of Canterbury, in the guise of a retired wet-fish merchant.

He met Simon, now 71, when she was a 20-year-old ingenue on holiday in London and he was a 30something rake.

The encounter "would prove crucial to the rest of my stay, not to mention life", she wrote in her memoir.

Donaldson promised marriage and introduced her as "the next Mrs Donaldson". She was packing her belongings in preparation for a new life in England when she received a letter from him: he was dumping her for actress Sarah Miles.

Donaldson had married twice by the time Simon wrote You're So Vain and would go on to marry for a third time.

He later called Simon "the answer to any sane man's prayers; funny, quick, erotic, extravagantly talented". He died in 2005.