Love letters written by Mick Jagger to American actress Marsha Hunt during the summer of 1969 have been auctioned by Sothebys for more than twice the expected sum. An unidentified buyer paid over $300K for 10 passionate, revealing letters that came during a time of much turbulence for the Rolling Stones frontman.

In fact "turbulent" is an understatement. In the weeks and months before penning the missives during the shooting of the movie 'Ned Kelly' in Australia, Jagger had fired and buried guitarist Brian Jones and watched his relationship with singer Marianne Faithfull slowly fall apart. It seems like his secret affair with Hunt was something he leaned on during a difficult time. They dated in secret and eventually had a child together before separating.

Hunt, who inspired the band's 1971 hit 'Brown Sugar,' was an American-born actress and model who was enjoying success in London as the star of 'Hair.' She graced the cover of many magazines and was eventually asked by the band to appear in a publicity photo shoot for the single 'Honky Tonk Woman.' She declined, but Jagger later showed up at her flat and the romance bloomed. The interracial relationship was initially kept a secret.

According the listing at Sotheby's, Jagger muses (albeit only briefly) about everything from the death of Jones to his failing relationship with Faithfull. He shares his enthusiasm for an acting career, pens lyrics for the song 'Monkey Man' and offers opinions on pop culture (“… John & Yoko boring everybody …”).

Hunt sold the letters because she need the money to repair her house in France. The now 66-year-old Hunt and Jagger still keep in touch and the famous rocker has been active in their daughter Karis' life.