Louis Mountbatten, 1st Earl Mountbatten of Burma, generally known as Lord Louis Mountbatten or "Dickie" is the uncle of Philip, Duke of Edinburgh. He is played by Greg Wise.
Lord Mountbatten first appears in Wolferton Splash congratulating his nephew after he's been knighted. He is later seen at the wedding standing next to Philip before sitting with his wife. Winston Churchill comments how he's the man who gave away India. Mountbatten is next seen getting his picture taken with his nephew, sister, and new niece after the wedding.