Vivien Rook noted that Lucy Saxon, being the wife of Prime Minister Harold Saxon, was Britain's First Lady. (TV: The Sound of Drums [+]Loading...["The Sound of Drums (TV story)"])
The United States had a title of First Lady. Those who held the title included the wife of Woodrow Wilson, (PROSE: White Darkness [+]Loading...["White Darkness (novel)"]) Jackie Kennedy, (PROSE: Who Killed Kennedy [+]Loading...["Who Killed Kennedy (novel)"]) the wife of Ronald Reagan, (PROSE: The Assassin's Story [+]Loading...["The Assassin's Story (short story)"]) and the wife of Felix Mather. (PROSE: Trading Futures [+]Loading...["Trading Futures (novel)"])
At Kerb!am, the Thirteenth Doctor used psychic paper to make Judy Maddox believe that she and Team TARDIS were relatives of the First Lady. When Judy found that the Doctor had a binary vascular system, the Doctor claimed it to be courtesy of the First Lady. (TV: Kerblam! [+]Loading...["Kerblam! (TV story)"])
Behind the scenes
In the real world, the spouse of the British Prime Minister is not officially called the "First Lady".