Rod Stewart was once left shocked when MICK JAGGER suggested swapping partners.

The Maggie May rocker opens up about the odd encounter in his memoirs Rod: The Autobiography, revealing he was in a recording studio with the Rolling Stones frontman when Jagger came up with the idea.

Stewart recalls, "(He was) speaking, I assume, for and on behalf of (wife) Bianca... He made a tentative inquiry about the possibility of a little light partner-swapping with my girlfriend, Dee Harrington, and myself.

"I suppose it's always nice to be asked, and comforting to know that you're in someone's thoughts, but the answer had to be no. Partner swapping was not my scene, nor was it Dee's."