13 May

13 May was Ux Census Day on the planet Ranskoor Av Kolos. As the species only ever had two living members, the census took approximately eight seconds to complete. (PROSE: Time Traveller's Diary)

In 1593, Christopher Marlowe was recorded as having died. (PROSE: All Done with Mirrors)

According to one account, Marlowe's "death" was actually the Fourth Doctor posing as him and pretending to die, to allow history to take its course. In reality, Marlowe lived on and assumed his alternate identity, William Shakespeare. (PROSE: All Done with Mirrors)

Another account stated that Marlowe had travelled to the colony of Roanoke in what would later be the United States to spy on Sir Walter Raleigh. While there, he and the rest of the colony were abducted by the Greld, who would use them in their plan to sabotage the Armageddon Convention. In this version of history, he actually died in 1609 as a result of a duel. (PROSE: The Empire of Glass)

Claire Brown was born on this day in 1985. When she was subject to a polygraph test in 1967, Claire accidentally gave her real birthday, 13 May 1985, but "corrected" herself, giving 13 May 1935 instead. (TV: Village of the Angels)

Behind the scenes
Christopher Marlow is an example of how the Doctor Who universe differs from the real world. Marlowe actually died on thirty May, not thirteen as in the DWU.