When the series was over I googled the Mountbattens together and separately and found out that these two sophisticated people were sexual acrobats. Both of them bisexual. Their marriage was an "open" one and they each had countless affairs, some of them outrageous. She was accused by a tabloid of having an affair with the black American singer Paul Robeson, who it turns out she had never met in her life, (she was really having an affair with a black nightclub singer, the details of which made me blush). The Windsors (the king) forced the Mountbattens to sue for libel and through considerable lying and deceit (and because it wasn't Paul Robeson but someone else) they won the case and were not socially ostracized as they would have been if they had lost.
She died at age 59. He died in his seventies, blown up in his sailboat in Ireland by the IRA.
So there you have it. Learn history from Masterpiece Theater. Learn the scuttlebutt on Google. Education is so broadening.