A collection of love letters written by Mick Jagger to American singer Marsha Hunt has sold at auction for £187,250. They are believed to be the inspiration for the band's hit single Brown Sugar.

According to Sotheby's the 10 letters had been expected to fetch up to £100,000.

The letters were written to Hunt, the then face of the West End production of Hair, in July and August 1969 while Jagger was filming Ned Kelly in the Australian outback.

At the time, his relationship with Marianne Faithfull was under strain - she was due to play the lead role in the film but attempted suicide in Australia and went back to England.

Jagger's relationship with Hunt, with whom he had his first child, Karis, was kept under wraps until 1972.

The letters were the centrepiece of an English literature and history sale at Sotheby's which also also included song lyrics and a Rolling Stones playlist.