Jeffrey Epstein joked that Lord Mandelson marrying Princess Beatrice could be considered incest, emails appear to show.
In an apparent email exchange on 5 October 2009, Epstein told Mandelson he could "marry princess beatrice" and that "the queen would have a queen as a grandson".
Mandelson appears to have replied: "Remember, I am already her Lord President", to which Epstein wrote: "Does that make it incest, how exciting".
Mandelson is openly gay and was in a long-term relationship with Reinaldo Avila da Silva, now his husband, at the time of the email exchange.
Mandelson has previously said: "I was wrong to believe Epstein following his conviction and to continue my association with him afterwards. I apologise unequivocally for doing so to the women and girls who suffered."
Epstein pleaded guilty to state charges in Florida in June 2008: one count of soliciting prostitution and one of soliciting prostitution from someone under the age of 18. He was sentenced to 18 months in jail and under a secret arrangement, the US attorney's office agreed not to prosecute Epstein for federal crimes. Epstein served most of his sentence in a work-release programme that allowed him to leave jail during the day to go to his office, then return at night.