VE Day
From Tardis Wiki, the free Doctor Who reference
VE Day marked the Allies' victory over Nazi Germany in World War II and took place on 8 May 1945. A major celebration took place in Trafalgar Square in London. (BFA: Casualties of War, QR: Magic of the Angels)
The Seventh Doctor's companion Hex was unaware of VE Day before witnessing the event in person. (BFA: Casualties of War)